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Патент USA US3078412

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G. E. MATHIAS ETAL
METHOD AND APPARATUS FOR SYNCHRONIZED DRIVES
Filed 001;. 20, 1958
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WITNESSES
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INVENTORS
Roberi W. Egglesione
Gerald E.Ma1hiqs 8
Charles G. Helmlck
W
ATTORNEY
'Jr'
‘
Feb. 19‘, 1963
G. E. MA_THlAS ETAL
3,078,402
METHOD AND APPARATUS FOR SYNCHRONIZED DRIVES
Filed Oct. 20, 1958
9 Sheets-Sheet 2
3
25E5
Feb. 19, 1963
G. E. MATHIAS ETAL
3,073,402
METHOD AND APPARATUS FOR SYNCHRONIZED'DRIVES
Filed Oct. 20, 1958
9 Sheets-Sheet 5
UCONTIRL
Feb. 19, 1963
3,078,402
G. E. MATHIAS ETAL
METHOD AND APPARATUS FOR SYNCHRONIZED DRIVES
Filed: Oct. 20, 1958
9 Sheets-Sheet 5
Fig. 5
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Feb. 19, 1963
e. E. MATHIAS ETAL
3,078,402
METHOD AND APPARATUS FOR SYNCHRONIZED DRIVES
Filed Oct. 20, 1958
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Feb, 19, 1963
e. E. MATHIAS 'ETAL
3,078,402
METHOD AND APPARATUS FOR SYNCHRONIZED DRIVES
United States Patent 0 "
3,078,402
Patented Feb. 15, 1963
s
r.
at a relatively high speed, the ratio ‘of the latter speed
3,078,462
to the former speed may be of the order of 2 or 3:1. I
METH’IDD AND APPARATUS FOR
During a complete operation the loading of any press
. SYNCHRUNEED DRlVES
Gerald E. ~Mathias, Clarence Township, Erie Qounty,
N.Y., Charles G. Heinrich, in,‘ Pittsburgh, Pa, and
Robert W. Egglestone, West Hartiiord, Conn, assiguors
to Westinghouse Electric 'Qorporation, East Pittsburgh,
relative to the others may vary over a wide range. At
the start of an operation, the raw material for the first
work item is seated on the ?rst die whileythe others-are
unloaded. One press is at this time heavily loaded while
the other presses are unloaded. During the succeeding
cycle two presses, are loaded while the others vare'un
10 loaded. This continues until all the presses are loaded.
This inventionrelatcs to the control or regulator art
with all the presses loaded, ‘the loadon the different
and hasparticular relationship to the control or regula
drives during the‘ loading part of each of the cycles may
tionof drives which are subjected to heavy loads that may
,vary Widely. One of the presses may be carrying out
1%., a corporation of Pennsylvania
Filed Get. 20, 1958, Ser. No. 768,194
9 Claims. (Cl. 318-172)
vary over a wide range during eachcycle of operation.
a forming or drawing operation and subjecting‘ its drive
Application Serial No. 670,318, ?led July 5, 1957 to Ger 15 to a heavy load while at‘ thesam'e' time another of the
ald E. Mathias and Robert W. Egglestone ‘for “Syn
presses may be performing atrimining operation sub
chronized Conveyor Control” and assigned to Westing
house Electric Corporation is incorporated in this appli
cation by reference.
.
The apparatus ‘to which the invention disclosed in this 20
application is particularly applicable is typi?ed by a line
of progressively operating presses which form work, say
metal sheet, intoa ?nished product, for example, a body
jecting its drive to a relatively low load. vAt the com
pletion of a series of operations, thepresses are gradually
unloaded in the inverse order to their loading during'the
start of an operation.
‘
v
i
i .
vUnder these variablegloading conditions, it is desirable
that .the presses and their drives be. synchronized. Syn
.chronization bymechanically linking the ,drives is ‘not
part of an automotive vehicle.
Such apparatus includes
satisfactory, because the linkages are subjected to enor
a‘plurality of dies‘on each of which the work is subjected 25 mous stresses andgdii?culty is encountered in providing
to pressure exerted by a press.
The work after being
_,treated on one die is moved-from this die to a succeed
ing die and following each movement is subjected to pres—
adequate-linkages which are capable, of responding with
the speed required to the changes in the loading of the
drives.
sure by the press of the new die until after treatment in
It is then a speci?c object of this invention to provide
the last die o-fthe series, the ?nal product is achieved. 30 a method andrapparatus for synchronizing a plurality of
Each press is moved continuously by amotor driven crank
mechanism repeatedly engaging and formingthe work.
As each press engages the work it exerts increasing pres
mechanically v disconnected drives. which are vsubjected to
highly variable ‘loads of high magnitude that may be
different for the .dilierent'drives.
I
sure on the work untilthe press passes through a dead
Another speci?c objectof this invention is ‘to provide
center position where it exerts the maximum pressure 35 apparatus forjsynchronizing a plurality ofdrives which
onthe work.
are not connected mechanically but ,whichare required
‘Each press drive is provided with a ?ywheel which
tooperate together and which are subjected vto highly
stores energy during the part of a cycle during which the
variable loads Whichmay differ forthedilierent drives.
drive is lightly loaded and releases energy during the 40
A further speci?c object ofthisinvention is to provide
. part of the cycle during which the drive is loaded.
a method and apparatus for coordinating the, speeds and
The loading imposed on the press drives by the di?er
the ‘positions of a plurality-ofdrives subjected to highly
~ent presses may be relatively high. For example, in a
variable loads sothat the drives operate together in the
‘typical situation, the loading may be .1200 inch-tons.
desired manner.
.
>
Each press drivemust lbecapable of delivering substan
An incidental object ofrrthis invention is toyprovide a
tia1~power,~say of the order of 400 to 1000‘ horsepower.
novel method. of speed control havingrgeneral applicability
It is desirable that the work be produced at a relatively
high speed and the presses rnust operate-at av correspond
ingly high speed. A speed of 25 strokes or cycles per
_ minute foreach press is typical.
It is desirable that all presses work together in forming
‘the work and that thepresses be so synchronized that
their compression operations be carried out after the Work
has been properly seated. on the die .and the mechanism
for advancing the work has been retracted to its standby
position and it is broadly-an-object of this invention to
provide a. method and apparatus for accomplishing such
synchronization.
but particularly suitable for the coordination ofthe oper
ation of a plurality of drives-which are operated together
.but which are subjected to highly variable large loads
diiferent for. the different , drives.
Another incidental object'of this invention is to provide
a-novel. method of controlling ‘the speed of a plurality of
drives, the operation of ‘which is to be synchronized so
> that theyv operate together and which are subjectnto high
ly variable largeloadsdiilerent for the diiferenhdrives.
This invention arises from the realization that the drives
need not be maintained at the same speedsandat the
same relative positions duringtheir entire cycles ofoper
.In arriving at this invention, it was realized from a
ation. vIt is only necessary that the speeds and relative
study of the operation of the apparatus to be controlled 60 position of the drives be suchthat they startthe c_orn~
that this apparatus has certain highly unusual operational
pressing operation together at a prescribed speedand that
features. Each drive passes through a cycle during one
they repeatedly reach, the starting speed priorto‘the start '
part of which its associated press is compressing or
of each of the succeeding compressing operations. a _It_ has
otherwise drawing, forming, or trimming the work and
been realized then that therdrives-may bepermitted to
during another part of which its associated press is mov
reach diilerentspeeds andtobecomedisplacedin posi
ing away from the Work and the work is being advanced.
tion with reference to each other to a, limited extenddur
During the forming part of the cycle, the press and. its
ing the loaded part of the cycle provided that they ‘are
drive are heavily loaded and during the work-moving
reset to operate together at a set speed during the un
part of the cycle, the press and its drive are very lightly
loaded part of the cycle.
loaded. During the loaded part of the cycle, the drive
In accordance with thisrinventionl inits speci?c aspects
‘maybe constrained to move at a. low speed and during
- the drives, include no mechanical interconnection butare
"the unloaded part of the cycle the drive isfree to move
provided with electrical interconnectionsxwhich:permit
aoraees
the speeds of all drives to decrease once the speed of at
least one of the drives drops below a predetermined set
magnitude. This limits the position deviations of the
drives from each other.
As to the position deviations
which do occur, the electrical interconnections operate
in dependence upon the position deviation of each drive
fromthe average position of all ofthe drives to bring
the drives to the same relative positions. The correc
tions in speed and position are etfected during the un
loaded part of the cycle so that the drives are positionally
and in speed together just before the loaded part of the
A.
‘FIG. 8 presents a series of vector diagrams showing the ‘
potentials derivable from the position following elements »
under the conditions illustrated in FIG. 7;
FIG. 9 is a circuit diagram illustrating in detail the
speed control system of the apparatus shown in FIGS. ‘
4A, 4B and 4C; and
Ft”. 10 is a circuit diagram of a modi?cation of this 1
invention particularly applicable to a two-drive line.
The apparatus shown in FIG. 1 is a press line includ- ing a plurality of dies on which work W1, W2 and W3 ‘
is to be formed. The work may be moved onto the lead- '
ing die (Wit) and off the last die (W4) and from die
‘
to die by retractable ?ngers 21 carried by, and linked to,
In accordance with a speci?c aspect of this invention,
transfer bars 23. The fingers 21 and the bars 23 are
speed control apparatus is provided which includes a
master speed reference for all of the drives. This speed 15 actuated by mechanisms (not shown) which are mechan
ically tied to the drive for one of the presses and are
reference cooperates with regulators connected to each
thus synchronized with this one press. The ?ngers 21
of the drives to tend to maintain the speed of each of the
cycle starts.
drives at a magnitude corresponding to the reference so
long as the speed of all drives is above a predetermined
magnitude. When the speed of any drive drops below
this predetermined magnitude, a portion of the master
speed reference parameter is absorbed externally to the
regulators so that the regulators all operate to tend to ad
just the speeds of the drives to a new reference corre
sponding to the lower speed of the drive which has dropped
to a speed below the predetermined magnitude. When
the speeds of all the drives returns to the predetermined
magnitude, the master speed reference parameter again
becomes effective and the drives are returned to the speed
corresponding to this master reference. For this purpose,
it is important that each of the drives be supplied with
power and be capable of drawing adequate power for
are movable relatively to the bars 23 into engagement
with the work and the bars 23 are movable to advance the
ting rs 2.1 with any work they are carrying or to return
the ?ngers for each now advancing operation.
Each press (not shown) of the press line is actuated
by a crank (not shown) which operates continuously as
it is continuously driven by an associated drive. The
cycle of operation of a press (not shown) of the press
line is shown in
2 and PEG. 3 shows the circular
movement of the driven end of the crank (not shown)
which drives a press in a typical situation. FIG. 3 is
labeled to correspond to FIG. 2 and in addition it in
cludes the points BBC, the bottom dead center at which
the work is subjected to the highest stresses, and TDC,
top dead center where the press is most remote from the
work.
the necessary acceleration from the lower speeds to the
it is assumed that in FIG. 1 the ?ngers 21 are in a
speed corresponding to the master reference.
In actual practice, the speed of one or more of the 35 position where they have seated the work W1, W2, W3
drives drops below the predetermined magnitude during
on the dies and are about to be retracted.
This corre
sponds to points A of FIGS. 2 and 3.
the loaded part of the cycles. All drives are then per
The ?ngers M are retracted between A and B of the
mitted to drop to a lower speed by the reduced speed
cycle and the return of the bars 23 to the back position
reference parameter. During the unloaded part of the
cycle adequate power is supplied to the drives to pro 40 is started. During this part of the cycle the presses
move toward the work W1, W2, W3 engaging the work
duce the necessary acceleration to return the drives to
at a point in the cycle corresponding to B. Between
the speed corresponding to the master reference. At
parts B and BBC of the cycle the work is formed on
the start of the succeeding loaded cycle the drives are
the dies.
etwecn BBC and C the presses are retracted.
then back to their original speeds.
At point C, the bars 23 are in the extreme retracted po
The novel features considered characteristic of this
sition and the ?ngers 2T. are moved out to engage the
invention are disclosed generally above. The invention
Work. At point D, the ?ngers 21 are in engagement with
itself both as to its organization and as to its method of
the work. The leading ?ngers 21 are in engagement
operation together with additional objects and advantages
with raw material to be deposited on the leading press;
thereof will be understood from the following descrip
the fourth set of ?ngers 21 with W3 which is ?nished.
tion of a speci?c embodiment when read in connection
with the accompanying drawings, in which:
etween D and A the work is seated on the successive
dies. While the fingers are moving as described, the
presses are moving from positions corresponding to C
tion disclosed herein is applicable;
to position A.
PH}. 2 is a diagram showing the operation of the 55
The compressing and retraction movements of the
FIGURE 1 is a diagrammatic view showing a draw
ing, blanking or coining press line to which the inven
process line illustrated in FIG. 1;
FIG. 3 is a circular diagram showing the angular ex
tent of the different parts of the cycle of a press of the
apparatus illustrated in FIG. 2;
presses takes place during the part of the cycle repre—
sented by the arc BC.
In a typical case, the arc BC
subtends an angle of 150°. Thus, the compression part
of the cycle constitutes about 5/2.; of the complete cycle.
FIGS. 4A, 4B and 4C together constitute a circuit 60 The ?ngers 21 are moving into or out of engagement
diagram of a preferred embodiment of this invention With
with the work between parts C and D and A and B
which the method in accordance with this invention may
of the cycles and during these parts the presses must be
be conveniently practiced;
out of the way.
FIG. 5 presents vector diagrams corresponding to the
This invention arises from the realization that it is
position following elements or synchroties of FIGS. 4A, 65 not essential that the presses be so synchronized that
4B and 4C;
they are together continuously througout the cycle or
FIG. 6 presents a series of vector diagrams showing
stroke. It is only necessary that the presses be properly
the vector relationships of the potentials derivable from
positioned so that the compression part of the cycle
the position following elements of FIGS. 4A, 4B and
starts when the work is properly seated. That is, the
4C;
70 presses should be together at instant B. At instant C,
the positions and speeds of the presses may have de
the vector relationship between the potentials derivable
parted
from synchronization to a limited extent. The
from the position following elements when the positions
departure must not be such that any press is in the path
of certain of these elements are displaced with respect
75 of the ?ngers 21 as they start in. The presses are brought
to the others;
FIG. 7 presents a series of vector diagrams illustrating
auras-o2
5
' back together as the drives move during the unloaded
minal ofthe generator through amaster variablere
part of the work cycle between positions C and B.
In practice the bars 23 and ?ngers 21. are mechani
. sistor 51 .and associated variable resistor 53 individual
cally linked to one of the presses, for example, the one
corresponding to work W1. The drives for this one press
and the others are linked electrically in such a way as
to permit substantial change in speed and position during
the loaded part of the cycle and correction during the
to each winding, the winding WSR to the negative ter
minal of the exciter GS.
The exciter GS is also .con
’ nected in a circuit with each of the pilot generators
PG. This circuit extends. from the positive terminal of
the generator GS through the variable resistor 51, a
recti?er 55 individual to each generator PG,'the pilot
unloaded part. In a typical situation in which the load
. generatorto the negative terminal. The speed winding
ing is 1200 inch-tons and the speed of the presses is 25 10 WS of each of the magnetic ampli?ers MA is supplied
strokes per minute, the speed may drop as much as 5%
from. the associated pilot generator PG in a circuit eX—
during the loading part of the cycle, and the relative
positions of the drives may change correspondingly. For
tending from the positive. terminal of the generator, PG
through a variable resistor 57, the .Winding WS to the
the same loading where the rate of operation of the
presses is 12.5 strokes per minute, the speed may drop
negative terminal. The recti?ers 55 are so poled that
so long as theassociated pilot generator PG produces a
as much as 20% and the relative positions depart cor
voltage of a predetermined magnitude, current ?ow
respondingly.
The apparatus shown in FIGS. 4A, 4B and 4C with
which the invention is practiced includes a Drive Unit
and a Control Unit. This apparatus is supplied from
conductors L1, L2 and L3 which are energized from a
through the resistor 51 and through the pilot generator
from the speed referenceGS is blocked. Thus, thefull
voltage of the exciter GS is available as a speed refer
ence.
The ampereturns produced through WSR by the volt—
commercial alternating current supply through the usual
disconnects or circuit breakers (not shown).
The Drive Unit includes drives DRI, DRZ and DR?)
age of GS is balanced against the ampere turns pro~
' duced through windings WS by the associated pilot gen
erator PG. Thewindings WSR and WS are so poled
each of which has a drive motor M connected to control
in each magnetic ampli?er that the higher the ampere
turns of WSR, that is, the higher the Voltage ofGS, the
higher the voltage of PG required to counteract the
a crank (not shown) which drives the corresponding
press. The Control Unit operates to control the speeds
of the motors M so that the positions of the motors of
the drive units are properly related to the operation of
the ?ngers 21.
Each drive D'Rll, DRZ and D‘R3 includes in addition
ampere-turns of WSR. The voltage of PG depends on
Thus, the higher
the voltage supplied from exciter GS the higher the speed
' the speed of the associated drive M.
that a drive M is permitted to reach. As the total
to the motor M a generator G for energizing the motor,
voltage of the exciter GS serves to set the speed refer
a tachometer or pilot generator PG, a speed reference
ence, the ‘motors M are permitted to reach the maxi
generator or exciter GS and a magnetic ampli?er MA
mum speed. The motors M are thus. permitted to reach
for controlling the motor M. The motor M has a shunt 35 the maximum speed so long as all pilot generators PG
?eld winding 25 which may be energized from a direct
supply a voltage above a predetermined magnitude.
current supply. The supply is indicating only symboli
“When any of the motors M drops to a speed such
cally but usually derives its power from the conductors - that its pilot generator PG puts out a voltage lower than
L1, L2 and L3 through a recti?er. The positive and
the magnitude, current ?ows through the master resis~
negative terminals of the ?eld supply are connected to
tor 53., the associated recti?er andthe generator absorb
the ?eld winding 25 through a variable resistor 27 which
serves to derive a potential proportional to the ?eld cur
rent.
ing part of the voltage from the exciter GS available
for speed reference. :The speed reference is thus re
duced for all motors M and motors are permitted to drop
The generator G has a series ?eld winding 29
The operation of the
to a lower speed.
motor M is controlled primarily by controlling the cur 45
The winding WB is supplied from a suitable direct
rent flow through the shunt ?eld winding 31. This iS
current source which may be varied to produce the
and a shunt ?eld winding 31;.
elfected by the magnetic ampli?er MA. The pilot gen
erator PG has a shunt ?eld winding 33 which is supplied
from a direct-current supply. The speed reference gen
erator GS also has a shunt ?eld winding 35 which is
supplied from a direct-current supply through a variable
~ resistor 37.
The resistor 37 serves to set the speed ref
erence at the desired magnitude.
The magnetic ampli?er MA includes an output Wind
ing W0, a position control winding WC, a speed refer
ence winding WSR, a speed winding WS, a biasing wind
desired bias. The damping Winding WDhas the func
tion of suppressing oscillation of the generator G in
response to surge. This winding is connected in a
circuit with the generator G which extends from one
terminal of the winding through a surge suppressing
capacitor 61, the generator G, the series ?eld winding
29, a resistor 63 to the other terminal.
The current
limiting winding WCL is connected in circuit with the
series ?eld winding 29 of the generator C and a recti
?er ‘65. The recti?er 65 is of the bridge type with two
- ing WB, a damping winding vWD and a current limit
of its opposite terminals connected across the variable
winding WCL. The output winding W0 is center tapped.
resistor 27 in series with the shunt ?eld winding 25 of
This winding is supplied from the conductors Ll and
the motor M and the other opposite terminals connected.
L2. These conductors are connected to the shunt wind 60 in series with winding WCL, a resistor 67 and the-series
ing 311 of generator-G through the winding W0 and
?eld winding 29. Current can only flow through the
through recti?ers ‘id, 43 and 45 which assure that the
Winding WCL if the potential across the series ?eld
current flow through the windings W0 is of such po
winding 29 exceeds the potential'impressed by the vari
larity as to produce a self-biasing effect characteristic of
able resistor 27. The variable resistor may be so set
magnetic ampli?er operation. The winding WC is sup—
that when the current through the series ?eld winding
plied from the Control Unit.
The control of the speeds of the motors M of the
three drives DRl, DRZ and DR3 is interdependent. The
connection of the speed reference windings WSR and
the speed windings WS of the magnetic ampli?ers MA
of the three drives is not individual to any one drive
but involves all drives. This connection is shown in
' FIG. 9.
The speed reference winding 'WSR of each of
the ‘magnetic ampli?ers MA is supplied from the gen
erator GS, in a circuit extending from the positive ter~
29 is excessive, current'?ows through WCL reducing
the current ?ow through the armature of the generator
G and the series ?eld winding 29.
The magnetic ampli?ers MA of the drives DRL DRZ
and DR3, the generator G and the motors M are con
trolled in dependence upon the relative positions of the
drives through the windings WC of the magnetic am
pli?ers MA which are controlled from corresponding
componnets oi the ‘Control Unit. The Control Unit
75 includes a plurality of synchrotiesSYl, 5Y2 and 8Y3
3,078,402
7
8
which are, in effect, rotary transformers capable of pro
ducing a position reference signal. Each synchrotie has
ZlTSl are connected to supply the alternating current ter
minals of 12R with the windings lTSiIl and ZlTSl so
a three~phase rotor ‘71 and a two-phase stator '73. The
brushes of the rotors “Ill are connected to conductors
connected that the potentials across these windings add
vectorially. In effect then, a potential equal to the vec~
Ll, L2 and L3 respectively and are thus supplied with
torial sum of the average potential derived from one pair
of terminals 75-77 each of SYl, 5Y2 and 8Y3 and the
potential derived from the other set of terminals 7 9—-8l of
ponents of which have phase positions dependent on the
SYT. is impressed on the alternating current terminals of
positions of the rotors 71, is then derivable from each
121‘. Similarly, windings llTSl and ZTSlll are con
stator 73. Each synchrotie has two pairs of terminals
75 and 77 and '79 and 31;. Single phase alternating po 10 nected to the alternating current terminals of HR in
such a sense hat the vectors representing their potentials
tential is derivable from each pair and the potential for
are additive. in this case, the pore- tial impressed on the
one pair of each synchrotie is displaced in phase by 90°
alternating current terminals of the recti?er HR is equal to
with respect to the potential of the other pair.
the vector sum or" the average potential derivable from the
The rotor “ll of SYl is mechanically connected to
the motor ‘d of drive DRE, the rotor of SYZ to the 15 pairs of terminals 79-81 of SYll, 8Y2 and 8Y3 and the
potential derivable from the pair of terminals '75—77 of
motor M of DRE and the rotor of 8Y3 to the motor M
three-phase potential.
Two-phase potential, the com
or"- DRE)’. The connection may be directly to the motor
M in each case or to the crank which drives the asso
ciated press. The connection in each case is rigid so
that the rotor of the synchrotie has a position corre— 20
3Y1. The direct current output terminals of the recti~
tiers 11R and
are connected to supply a resistor 161.
The positive terminal of this resistor l-tll is connected
to one terminal labeled —i-A of the Winding ‘WC of the
sponding to the position of the crank or to the position
magnetic amplifier MA of drive
of the corresponding press.
secondaries lTSlZl and ZlTSll are connected to supply
recti?er 13R. In this case, the windings are so connected
"
The Control Unit also includes transformers ll'i“, ‘l'iT,
131’ and 23.1", 221" and 231'‘. The primary ilTP of
HT‘ is connected to one pair of terminals 75—77 of;
SYl, the primary iii/1T? to a corresponding pair “FE-J77
0t SYE and the primary EST? to a corresponding pair
'75-'77 of 8Y3. Primaries llTP, lZTP and 131'‘? then
carry alternating current supplied by the associated syn
chroties respectively and displaced in phase in depend
ence upon the angular displacements of the rotors of
the associated synchroties from initial settings. The pri
marries ZlTP, ZZTP and
are similarly connected
to the other pairs of terminals '7l)~—$}l or S‘r’l, 5Y2
that the potential across the alternating current terminals
of 13R is equal to the vectorial difference of the potentials
across .lTSlZ and. ZTTSZ. The potential across the alter
nating current terminals of 133 is thus equal to the vec
torial ditierence of the average potential across the cor
responding pairs of terminals 75—77 of SYl, SYZ and
8Y3 and the other pan of term nals 7§——8l of SYl.
Secondaries .‘rlTSZ- and ZTSlZ are similarly connected
to 15R. Again the alternating potential across 14R is
equal to the vectorial di "ercnce of the potential derivable
from the corresponding pairs of terminals
of SYl,
the remaining terminals 75-77 of
and 5Y3 respectively. Each transformer llT, 1.2T, 35 3Y2 and Y5
SYl. The direct current terminals of rectifers 13R and
EST, 2311", 5.2T, 23?." has a pair of secondaries llTSl
are connected to supply a resistor
the positive
and ill-S2, 1ZTSI. and lZTSZ, l?TSl and HTSZ, ZlTSl
and ZlTSZ, ZZTSl and Eli-T32, 2318i and 23TS2, re
spectively.
The Control Unit also includes a pair of transformers
IT and
Each of these transformers has three pri
mary windings l'l‘hl, 1T '2 and lTPE and ZTPE, ZTP’Z
and ZTFS. The windings lTPl, lT-‘PZ and lTPS preter
ably have an equal number of turns as do the windings
ZTPFL, ZTFZ, ZTPS. The primaries lTl’l, TYPE and 1TF3
are connected in a series network with corresponding pairs
of the terminals 75 and '77’ of S‘r’l, 8Y2 and SYS with
the pairs of terminals 75 and '77 sandwiched between the
primary windings lTFl, ItTPZ and lTPS. This series net
work extends from one of the terminals 77 of SYl through
lTPl, a conductor 83, the terminals 75-31"? of 8Y2, a
terminals of which is connected to the remaining terminal
of the winding WC of DRE which is labeled +B. +A
and
connected
+3 aretoelectrically
the negative
positive
terminals
relative
of to11R,
conductor
12R, 13R
and 14 ..
The polarity and magnitude of the current
flow through WC is dependent on the relative magnitudes
of the potentials across ‘he corresponding resistors ltll
W5.
Recti?ers
and 21R, 23R and 24R, 32R and MR
and 33R and
are similarly connected in pairs to sup
ply resistors 1557 and Trill‘, and 111i and lid respectively,
the positive terminals of which are connected respectively
to the conductors +6
+3 of the winding WC of
the magnetic ampli?er MA of DRZ and to conductors
-+E and —{—F of the winding WC or" DRE. In each case,
signals are produced proportional respectively to the sum
of and the di?erence between the average potential de
of 8Y3, a conductor
conductor
85, lTPZ, a89,
conductor
llTPS, to‘57,
thethe
remaining
terminalsterm. ll
'75 of S‘Yll. The total potential impressed in series with
and 77 or 79
the windings lTPl, lTPZ and lTPS of 1T is then equal 55 rived from one pair of output terminals
and 81 or" the synchroties and the other pair of terminals
to the vectorial sum of the potentials across the sandwiched
terminals of S‘Yll, 8Y2 and 8Y3. The primaries Z-TPi,
‘‘
ETPZ and 2TP3 are similarly connected in a series sand
‘79 and $1 or 75 and '77 of one of the synchroties SYZ
and 5Y3 respectively.
The average potential derivable from the correspond
79 and 81 of SYl, SYZ and 8Y3. The transformer 1T 60 ing pairs of terminals of 8Y1, SYZ and 3Y3 has a phase
position dependent on the average phase position of the
has a plurality of secondaries ITSH, lTSlZ, ‘iTSZl,
wiched circuit with the remaining corresponding terminals
ITSZZ, lTSEl and lTSElZ. The number of turns of these
secondaries is equal to the number of turns on any wind~
rotors 71 which, in turn, is dependent on the average posi—
tions of the cranks (not shown\. The sums and di?er
third the potential impressed across the primary windings
so sets the corresponding generator G as to tend to cor
ences derived serve to provide an error signal which when
ing of lTPl, lTPZ or TTP3. Thus, the potential across
impressed
on the corresponding magnetic ampli?er MA
65
any secondaries lTSll through lTSSZ is equal to one
rect for the deviation in position.
For an understanding of the relationship between the
these windings. Transformer 2T has secondaries ZTSll,
Vectors representing the various potentials and between
ZTSTLZ, ZTSZR, 21'822, ZTSSZ and ZTSSZ similarly re
70 the potentials themselves, FIGS. 5, 6, 7 and 8 should be
lated to the primaries ZTPl, ZTPZ and ZTPS.
considered. in FIG. 5 vector diagrams a, b and c present
The Control Unit includes a plurality of rcctiiiers of the
lTPl, ITPZ and lTP3 or to the average potential across
bridge type 11R, 12R, 13R,
21R, 22R, 23R, 24R,
the potentials impressed on the brushes of the rotors '71
of the synchroties 5Y1, 3Y2 and 8Y3 respectively from
31R, 32R,
Each recti?er is of the bridge type
the conductors Lil, L2 and L3. The corresponding po
and has alternating-current input terminals and direct
current output terminals. The secondaries lTSll and 75 tentials derivable from the secondary terminals 75—~77
\- 3,078,402
4.9
and 79-Q‘dl are represented in the vector diagrams d, e
and f. VillTP corresponds to the potential derivable
- from one pair of terminals ’.F5—~77 of'SYl. ~This poten
tial is impressed across the-primary HTP as indicated by
ltd
vectors which in phase and magnitude arethe sameas the
vectors representing the potentials V11~TP,'.V'12TP,
V13TP, AVZETP, VZZTP and VZSTP of the correspond
ing primaries.
I the symbol. ~V2lTP representsthe potential» derivable
from the other set of terminals 79-bit and impressed on
a, b, c, d, sand 1‘ of PEG. 8 areas represented in this
- ZlTP.
view.
The potentials-VlllTP» and VZlTP are in quadra~
The vectorial sum of the various vectors in diagrams
Vll and V12 are new smaller than V13 and
ture. Vl2TP, VZZTP, VET? and V23TP are similarly
V14. The difference between the potentials derivable
related. ' Diagrams d, e and 7‘- represent the‘initial orstand
from-the rectifiers HR and .lZRand' 13R and MR (re
by settings of the rotors r‘l’l in which VlltTP, VlZTP and, 10' sistors ltl‘iand ms) is then a negative potential designated
V131"? are in phase and VZElTP, VZZTP-and ‘ 223T? are
—-Q in FIG. 8. V21, V22,‘ V23 and V24 are all equal
also in phase.
1 so‘ that the difference in the potentials derivable from the
a In FIG. 6, diagrams a, b and c present the relation
ship of the potentials impressed acrossthe alternating
- recti?er-s 21R and 22R and 23R and 24R (resistors N7 and
P199‘) respectively, is zero. Similarly, the diiference of
currentterminals of the various recti?ers 11R through. 15 the potentials derivable ‘from the recti?ers 131R and 32R
34R initially or during standby when the potentials de
and 33R and 3411 (resistors ill and‘ 113) is a positive
rivable from corresponding pairs of terminals 75—77 or
potential designated +Q in FIG. 8.
79-81 of the synchroties are in phase. In diagram a,
The potential supplied by the. pairs of recti?erst 11R
VllTSl and VZTSM are presented vectorially. These
and 12R, 13R and MR, 21R and 22R, 23R and.24R,
vectors are added and ‘their sum is V11. Diagram I)v 20 31R and 32R and 33R and 34R is a relatively smoothdi
shows the addition of vectors VlZTSl and VZTSZl- to
rectcurrent potential since in each case it is» derived
obtain vector V21. V31 is similarly obtained. V11,
by rectifying two—phase potentials, the separate compo‘
V21 and V31‘are in phase. Similarly, vectors V12, V22
nents of which are displaced by 90°. .The relatively
and ‘V32 are shown in'diagrams a, b and c of FIG. 6
small ripple does not affect the operation of'the appa
as the difference between V 11812 and VZlTSZ, V11‘S22. 25 tus.
and VZZTSZ, VlT'S3Z and VZSTSZ. In diagrams d, e
The potentials derivable from the various resistors
and J", V13, V23 and V33 are similarly derived as vector
are impressed across the windings .WC oi‘ the ampli?ers
sums as are also V14, V24 and V34.
MA in the drives DRLv D122 and D123. The potential im
The potential between conductor -[-A and the nega
pressed across» winding WC of DRl has a polarity such
tive conductor M5 is the recti?ed potential V11 or Vl2.>
that the current flows from +B- conductor to -]-A con
vThe potential between +13 and NS is the recti?er po
tential V13 or V14.
V11 and Vl-Z are equal as are also
ductor and a magnitude proportional to the ditference of
‘the absolute magnitudes of the vectors V13, VM and
V113, and V14. Thus the potential difference between
V11, V12. The winding WC of drive ‘DRZ is supplied
+A and +2» presented by the equation in FIG. 6 is
with no currentthrough conductors +0 and +D and
zero. Similarly the potential difference between +C and 35 the winding WC of drive DR?’ is supplied-with current
+13 is zero and the potential difference between +13 and
,?owing from conductor ~l-E to conductor +F having a
+F is zero. Thus with the synchroties in phase the
magnitude ‘proportional to the difference between the ab
windings WC of the magnetic ampli?ers MA of each
solute magnitudes of the vectorsVSiLV?Z and V33, V34.
of the drives DRl, DRZ, DR?) are-not supplied with cur
The effect of this current ?ow through the various wind
rent.
ings W0 is to cause drive DRll to'rotate slower than drive
FIG. -7 presents'the vector relationships which arise
DRZ and driveBRE to'rotate at a higher speed than
when there is a phase displacement between the rotors
drive DR2 so that ultimately the drives are pulled into
'71 of the synchroties SYll, SYZ and 8Y3. This ?gure is
synchronisrn. During this position adjustment the effect
based on the assumption that during the operation, the
of the speed control components of the respective drives
phase position of the cranks have changed so that the 45 may be such. that all drives‘are increasing in speed.
crank of~drive DRE. leadsithe crank of drive DRE by
In the standby condition of the press line, the presses
approximately 221/2 electrical degrees and the crank
will be in the position in which they stopped during‘the
of drive DR3 lags the crank of DRZ by 221/2 electrical
prior operation. A press line of the type under considera_
degrees. The phase relationship of thepotentials de
rivable-from the related pairs of terminals of 8Y1, SYZ
and 8Y3 is presented in vector diagrams a, b and c. The
summation of the vectors corresponding to the potentials
VMTP, VlETP, VISTP derivable from corresponding
pairs of terminals 75——77 of thc-synchroties SYI, SYZ,
8Y3 is shown in diagram d. ‘In’ this case, the vectors are
added to produce a sum equalto-3V1TP. One-third of
this sum is the average potential VllTS'which is the po
tion here usually includes relays or other like means to
assure that thepresses are stopped in an unloaded part
of the cycle or stroke. It may be assumed then that
the presses are stopped at some point between topdead
center TDC (FIG. 3) and A. Thetransfcr mechanism
is_rnechanically tied to one of the presses,'for example
to the leading press which operates on work W1 of‘FlG.
1. With the press stopped between TDC and A the ‘?n
gers Ziare inthe retracted position.
Inv standby the conductors L1, L2, and L3are con
tential across any of the secondaries of IT. Similarly,
VZTS is derivable by the summation of the vectors
Inected through the circuit breakers or disconnects (not
VZlTP, VQZTP and V231‘? which are the poten 60
(shown) to the commercial supply buses and are vener
tials derivable from the other corresponding pairs of
, terminals 79-—8s1l of the synchroties 5Y1, SYZ-and 5Y3.
gized. The synchroties 3Y1, SYZand SY3 may then
be supplied with three-phase potential and two-phase
FIG. 8 presents a series of vector diagrams similar to
potential may be derivable from their respective ‘ stators.
those ofPiG. 6 but with the phase displacement corre
sponding to FIG. 7, a, b and 0, rather than zero displace 65 The rotors of these synchroties are positioned together
corresponding to the positions of the associated presses.
ment (Flt-3,5, d, e and 1‘). In this case, the vectors rep
Potentials derived from corresponding pairs of terminals
resenting potentials derived from the transformers 1'1‘
75-77 and 7%431 of the synchroties SYl, SY2 and
and ET have a phase and magnitude equal to the average
3Y3 are then in phase. The drives DRL DRZ and DR3
potentials VlTS and VZTS which are derived in dia
grams D and E of FIG. 7. Thus, V2TS11 of-diagram a, 70 are controlled from a starting circuit (not shown); Such
a circuit would include contactors which would maintain
FlG. 8, has a phase and magnitude equal to VETS of
the drives ~DR1, DRZ and DR3 deenergized so long as a
diagram e, PEG. 7. Similarly, VlTSlZ has a phase
starting switch or .pushbutton (not shown) is open.
and magnitude equal to VllTS of diagram (1, FIG. 7.
The‘potentials of the secondaries of transformers HT,
121‘, and HT, 2-1T, ZZT and 231‘ are represented by
To carry out an operation a stack of the raw material
tov be formed is placed adjacent to-the leading die in a
aovaaoa
‘ll
position where the raw material units may be picked up
one by one by the ?ngers 21. To start the operation
the starting pushbutton (not shown) is closed energizing
the drives DRl, DRE and DRS. Initially the windings
WC of the magnetic ampli?ers MA are not supplied with
current since the secondary potentials VllTP, VlZTP,
V131“? and VZlTP, VZZTP, ‘123T? derivable from ter
minals 75—77 and 79—dl respectively of SYl, SYZ and
8Y3 are in phase.
The drives DRil, DRZ and DR3 are
l2
step. The presses are in step before point C is reached
during the succeeding cycle.
As the motors M and the presses continue to move,
the ?ngers 21 are again injected advancing the partly
formed work W1 on the leading die to the second die
and advancing raw material to the leading die. The
above described process is then again repeated but this
time two of the presses are loaded while the third is
unloaded so that a correspondingly different change in
controlled by the speed reference GS and since they are 10 speed and position takes place.
During the succeeding operation the ?rst leading die
unloaded the motors M soon reach a speed correspond
is loaded With raw material, the second die with partly
ing to this reference. The motors M move the cranks
formed work from the ?rst die and the third die with
which, in turn, move the presses. The presses being
the partly formed work from the second die. Now all
unloaded, the movement of the presses is substantially
synchronized. At the point A (FIG. 3) the retraction 15 three presses are loaded and a corresponding operation
involving the Control Unit and the Drive Unit takes
of the ?ngers is started and at point B the fingers are
completely retracted.
Since none of the dies carries
material to be formed the presses are unloaded as they
are moved by the cranks from the point corresponding
to B to BDC.
The presses then remain in the same rela
tive positions and continue to the point C.
At the point C, the ?ngers 21 start to move in. At
this time the bars 23 are in the extreme left-hand posi
place. The loading of the three presses may be di?erent
and the speeds and changes of positions introduced by
the different loadings may be different. Whatever the
relationship correction is effected by the Control Unit
so that the presses are all together at the point C (FIG. 3).
At the end of an operation the leading press is ?rst
unloaded, the second press next and the third press last.
The loading effect on the drives is then the converse to
with the leading press move towards the r w material. 25 the effect produced at the start of an operation.
in HS. 10 a modi?cation of this invention in accord
At point D the ?ngers associated with the leading press
ance with its broader aspects is shown. This view re
are fully engaging the ?rst unit of the raw material.
lates to a system for operating only two press units or
The movement now continues from D to A. At A the
like apparatus. The Drive Unit in this case includes two
?rst unit of raw material is deposited on the leading
tion with respect to FIG. 1 and the ?ngers 21 associated
press and the retraction of the ?nger 21 started. At B
the ?ngers are retracted.
A unit of material ‘(V1 is now seated on the leading
drives DR@ and DR5. Each drive DRd and D115 has
a magnetic ampli?er MAE which has two position con
trol windings WCE. and WCZ in addition to the other
die while the other dies continue unloading. As the
motors M continue to rotate the drive Dill is subjected
windings of the ampli?ers MA.
to a large load which reaches a maximum at bottom
dead center BBC. The other drives are unloaded.
The effect on the drive DRll of the loading of the
and 5Y5.
leading press is to reduce the speed of the corresponding
motor M substantially. This, in turn, reduces the poten
tial of the associated pilot generator PG so that current
can flow through the variable resistor 51 and through
the pilot generator PG of drive DRl. A portion of the
potential from exciter GS is then absorbed reducing the
reference speed potential supplied to the reference wind
ings WSR of all ampli?ers MA (FIG. 9). The speeds
of the motors M of drives DRZ and D113 are then re
duced substantially but since they are unloaded their
speeds do not reach the low speed of the motor M of
DRl. The leading press then is displaced in position
with respect to the other presses and the phase of the
The Control Unit in this case includes synchroties 5Y4
Each synchrotie has a rotor 131 to which a
three-phase potential is supplied from the conductors
Ll, L2 and L3 and a two-phase stator 133. The poten
tials from the pairs of terminals of the stator of 8Y4 are
supplied to transformers 41‘ and 5T respectively. The
potentials of the synchrotie 8Y5 is correspondingly sup
plied to transformers 6T and '71‘ respectively. The sec
ondaries dTSl and dTSl supply a recti?er 46R, the direct
current terminals of which are connected between a con
ductor labeled +H and a common negative conductor
13S. Secondaries STSl and '7TS1 correspondingly sup~
ply a recti?er 57R which also supplies direct current po
tential between conductors +l-l and conductor 135. The
current between conductors +H and 135 ?ow through
windings WCZ of the magnetic ampli?ers MAl. Second
able from SYZ and 3Y3.
aries dTSZ and éTSZ and 5TS‘2 and '7TS2 are similarly
connected to supply direct current between conductors
+0 and 135 through recti?ers 64R and ‘75R. The cur
rent flow supplied by recti?ers 45R and 57R and 64R
At point BBC, the leading press and drive DRl is
unloaded. The speed of this press increases correspond
ingly permitting the speeds of the other presses to in
crease. Eventually, the speed of the leading press reaches
a magnitude at which the associated pilot generator PG
8Y4 and 8Y5 and effects an adjustment in the drives DRll
and DRS so that they become synchronized during the
unloaded part of their strokes or cycles.
To facilitate a complete understanding of the invention
potential derived from the synchrotie SYl is correspond
ingly displaced (lags) with respect to the potentials deriv
of drive DRl produces a potential such as to block
current flow to the variable resistor 51. At this point
the full potential of the speed reference generator GS
takes effect so that the motors M of all drives DRE, D112
and D113 are permitted to reach full speed.
While this change of speed operation is taking place,
the relative positions of the presses are also being shifted
because of the operation of the Control Unit. Initially
the leading press lags with respect to the presses driven
by drives DRZ and D113 and thus with respect to the
average position. The current flow through WC of
drive DRll is then from +A to +3. Correspondingly
the current flow through the winding WC of drives DRZ
and DR3 respectively is from +D to -|—C and from
+F to +E respectively. The motor M of drive DRE
then is accelerated at a higher rate than the motors of
drives DR2 and DR3 and eventually the presses pull into
and 75R depends on the relative positions of synchroties
disclosed herein, the following summary is presented.
The invention in its speci?c aspects relates to apparatus
for maintaining the angular position of the cranks of a
plurality of presses within a given angular tolerance. The
presses may be drawing, blanking or coining presses with
each press obtaining energy from a ?ywheel to supple
ment the synchrotie torque during the working portion of
the press cycle. It is necessary for the speed of the press
to decrease to release energy from the ?ywheel during
the working cycle. Due to the press slowdown or speed
regulation the angular velocity of the press crank is not
constant. It is not desirable to have an angular position
reference which has a constant angular displacement.
It is desired to have an angular position reference which
has an annular position time characteristic similar to that
attained on a press actually doing work during its load
cycle.
if a given press were to serve as master angular
acres-ea
.13
> lili
. position reference, it would be necessary to choose a press
vidual secondary winding is actually one-third the vector
which is the average of the. presses in thevline in the
amount of speed regulation. Even with choosing such a
press its position reference would be incorrect when the
sum of primary voltages. In FIG. 5 it has been assumed
that the secondary vectors of motors More in phase.
The-secondary voltages derivedfrom 1T, are foreach
secondary equal to VliTP, V12TP and VESTP. The
vector for the secondary voltage IT is then the average
vector of VllTP, V121"? and Vl3TP. This is a refer
-. press line is actually being loaded or unloaded. The press
line is considered ‘being loaded whenmaterial is being
fed to. thestart of the line with the press-es at the end of
the line having no material. The press line is considered
being unloaded when no material is being fed to presses
ence vector.
The same addition is applied to vectors of VZlTP,
. at the start of theline but material is still being worked
VZZTP and V23TP to arrive at a reference vector corre
at ‘the end ofthe line. Toobtain a position reference
sponding to each of the. secondary voltages of 2T. This
' which is not determined ‘by the loading on any single press
is also a reference vector which lags the reference vector
a reference which isthe average instantaneous angular
from ET by 90 electrical degrees. Thus assume,
, ‘position of all units is in accordance with this invention
selected as a reference. This position reference signal
is. then compared to the position signal of each press and
a signal issent to the regulator corresponding to each
1 press indicating whether the press position involved is
. in phase ahead of, or behind, the position reference.
The unit which is coupled to the press crank shaft con- .
sists of awound rotorsynchrotie which has a three-phase
_ primary and a two-phase secondary. FIGS. 4A, 4B and
' 4C. showth-e circuit diagram of three such position de
. and when VlllTP,‘ VllZTP, V132"? are in phase
tection unitsSYll, SYZ and 5Y3. The primaryof each
of theseunits is on the rotor 71 .andis excited from a 25
common three-phase power supply Ll, L2 and L3. The
two-phase secondary is on the stator member '73 in each
VTTS: VMTP= VllZTP: Vll3TP
similarly
VETS: VZlTP: V22TP= V23TP
. case and has a voltage induced into it by the rotating ?eld
~ ‘of. the primary member. The phase relationship between
To obtain an electrical signal which indicates the rela
tive position of each press tothe, reference vectors a vector
the primaryand secondary voltages in any synchrotie SYl,
addition method is applied. Input to the regulators shown
.ISYZ and 3Y3 or between secondaryvoltages of different
on FIGS. 4A, 4B and 4C can be described as push-pull
two-phase signal error. FIG. 6 shows the vector relation
vunits depends upon the. rotor position of thesynchrotie.
FIG. 5 shows the vector relationship of the primaries
.and secondaries of. the synchroties- 5Y1, SYZ andSYS
when thesynchro-ties are in the same relative position with
respect toeach other. . Since the primary 71 of each unit
ships which exist with thethree synchroties in phase and
are the vector sums of the potentials on transformer sec
ondaries shown in FIGS. 4A, 4B and 4C. The polarities
‘ ‘is excited from a common three-phase power supply :the
1 primary vectors are in phase and are represented, by
of the transformers are indicated in FIGS. 4A, 4B and4C.
. synchroties. SYl, SYZ and 8Y3 are representable by ro
signal between +13. and lltl5..- Vector diagram at on FIG.
6 shows the vector addition of VMTS andVZTSll to
obtain V11 which is the voltage applied to recti?er 11R.
Vector VlTSlZ and minus VZETS providesfor the vector
Four recti?ers are used in each of the three position
signal circuits, Considering the circuit of synchrotie 8Y1,
vectordiagrams a,.b and c. Vectordiagrams like, and f
' correspond to the stators '73. Since the primary is excited 40 recti?ers 1111, 12R, 13R, 14R are included. Recti?ers
11R and 12R provide for a two-phase full-wave recti?ed
froma three-phase power supply tjhe .vectorsVZll, V12
signal between +A and 105 for .one side of the push-pull
\ .and Vll3,are rotating, rotation in.the counterclockwise
signal. Recti?ers 13 and 141 provide a two-phase full
;. direction vbeing assumed. The. alternating current volt
wave recti?ed-signal for the one half of the push-pull
ages induced into the, two-phasesecondaries 7370f the
‘tati'ngvectors which rotate in the counterclockwise direc
tion. NVith thesynchroties at rest the speed of rotation
. oftheprimaryr and secondary vectors is equal and if the
. sum of V12 which is the voltage applied to recti?er 12R.
power supply is 60‘ cyclesthey rotate at 607CYCl€ fre
-
Note that V11 and V12 are 90° apart in time, hence, the
output voltage between +A and M35 is a full-waverrecti
. ?ed two-phase potential with the magnitude of the. voltage
between +A andltlS proportional to the magnitude of
vectors V11 and V12.
In FIG. ,6, d shows the vectors for the voltages appear
. quency.
In explaining the operation it is assumed that the
.synchroties are of the four-pole type having rotating ?elds
rotating at 1800 r.p.m., and that the synchrotiesare di
rectly connected. tor-the crankshaft ofthe presses and the
> 1 press crankjshafts have a maximum speed of. 25 revolu
. ing across recti?ers ESRHand MR, withVlS and V14 be
. tions per minute. It is also assumed that’the direction of
\
. ing the two-phase alternating-current voltage to be recti
?ed by these two recti?ers to provide a ,twophase full
rotationof the rotors '71 of theseunits is counterclock
wise. Sincethe rotatingy?eld from the rotor '71 of each
synchrotie andthe rotor are rotating in the same direc
Wave recti?ed voltage output between +3 and 1&5. Since
the magnitude of vectors V11, V12, V13‘ vand V14 are all
. ti'on the speed of rotation of the flux onthe stator mem
~ her is 1825 revolutions per minute. This causes an in
I : duced frequency of approximately 60.8 cycles per second
to be introduced in the secondary ofeach synchrotie.
. The average position reference vector is obtained by
addingvoltage vectors VllTP, VIZTP and VlE‘sTP vec
cto'rially and-dividing by 3. This is accomplished by add
.. ingthese voltages in sandwich series ‘with three of the
primary windings lTPTi, llTPZ and jlTPS. vThe division
by the factor of 3 is obtain by turns ratio between the
- primary and secondary windings of transformers lTPl,
'ITPZ and 1TP3. Since there are three of these primary
equal the potentional difference between ,+A.and +B
is zero; hence, no corrective action is sent to the regu
. later for correction of position.
The vector relationship for DRZ and DR3 areshown
in FIG. 6,_b, c, e and 7‘. Since these drives are also as
sumed to be inphase they have duplicate outputs with
‘zero output to ampli?ers MA.
In FIG. 7 is shown anothercondition of the vectorrela
tionships to illustrate the signals. obtained, 8Y1, 221/2 de
70 grees ahead of 5Y2 and 8Y3, 221/2 degrees behind SYZ.
windings, the turns ratio between each of these windings »
and each of- the secondary windings is equal. Since the
three primary windings are in series in the sandwich
series arrangement thevoltage appearing across an indi 75
The corresponding vectors derived from. the secondaries
of the synchroties 8Y1, 8Y2 and SYSareshown in dia
grams a, b, c, of FIG. 7. FIG. 7, d shows the vector addi
tion of VMTP, VlZTP and V13TP which divided by a
factor 3 gives the average VlTS.
The. magnitude of
T3
vector VlTS is now slightly less than the magnitude of
the position detecting synchroties are compensated. The
VlllTP, VllZTP or VTSTP. This decrease in magnitude
advantage of connecting the primaries of the transformers
of the vector, however, does not affect the operation of
for reference vectors in sandwich series with the various
the circuit since it appears in both phases of the two
voltages from the synzhroties 8Y1, 8Y2 and 5Y3 allows
phase circuit by the same amount. The phase relationship Ul a much greater range in the output voltages of the sec
between the voltages for Vii and VTZ is still 90° and
ondaries of these synchroties without exceeding low volt—
since the signal to the regulators is obtained from the
age class of insulation level. It also allows, if required,
push-pull circuit by comparing the magnitudes of V11,
with simple switching to eliminate one or more of the
V12 to the magnitudes of V3.3 and V14, both sides of the
press drives from the line.
push-pull circuit are slightly attenuated by this decrease in 10
In accordance with this invention, an angular position
magnitude of VHS and VZTS and no net result except
reference which is dependent upon the average angle of
for a slight decrease in output signal occurs. In actual
all units and a position error signal which is proportional
practice, the maximum displacement angle is anticipated
to the actual angular error of each press in respect to the
to be approximately 10 electrical degrees instead of 221/2;
reference, with the signal being zero for correct position
this gives a magnitude of VETS of 99% of the magnitude 15 and of different polarities for ahead and behind positions
of VHTP, VilZTP or VllZiTP. Since the affect of the
is provided. This arrangement also obtains a signal which
smaller magnitude of VlTS vector has negligible affect
is practically linear with angular error and which is not
on the performance of the system for the ease of explana
affected by change of recti?er resistance since all recti?ers
tion of the operation no decrease is assumed. The VZTS
are operating in a region where their forward resistance
reference vector is again obtained in the same manner as 20 is practically constant because of the phase recti?cation.
the V 1T8 vector (see KG. 7, e). VZTS vector lags VETS
FIG. 10 shows a modi?cation of the invention in ac
vector by 90 electrical degrees.
cordance with its broader aspects applicable where only
FIG. 8 shows the same addition of vectors as is shown
two presses are required to operate. This arrangement
in FIG. 5 except for the ahead of and behind phase posi
of only two presses does not require the obtaining of the
tions of 8Y1 and 8Y3 units. Referring to FIG. 8 a vector
V11 is obtained by the addition of VlitTSll and VZTSlll.
Vector V12 is obtained by the addition of minus VZlTS’7
average reference vectors but compares only the relative
vectors between the two presses. The output arrange
ment on FIG. 9 is shown as connected to two control
and VTTSTZ.
Note that the V11 and Vii). vectors are
windings WCi and WCZ of magnetic ampli?ers MAI of
still 90 degrees apart in time and their magnitudes have
been diminished due to the vector addition of the differ
drives DRd and DRE)‘. In this arrangement the flux addi
tion of the two windings on each ampli?er gives the net
ent angular relationship between the position vectors
VllTSi and minus VZTTSZ in respect to the reference
vectors V iTSiZ and VZTSH. FIG. 8, d gives the vector
results of the push-pull output of +6 and +11 to 135.
In this arrangement the polarities of the control windings
additions of VlTSllli, an average, and VZTTST from which
is obtained vector V313, and of minus VZTSTZ, an
average, and VlIiTSZ from which is obtained vector
V14. V13 and Vld vectors are 90 degrees apart in
time. The recti?ed voltage at +A to lldS is now
proportional to the magnitude of the V11 and V12
vectors. The recti?ed voltage at -]-B to 185' is now pro
portional to V13 and V14 vectors which are considerably
larger than the V11, V12 vectors. Therefore, +13 is at
a higher magnitude than +A and the current signal is
supplied to the drive DR}; with current ?owing from +B
of one drive DR4 are reversed with respect to those of
the other drive DB5 such that the current ?ows from 5 to
(hand 6 to 5 or '7 to 8 and 8 to 7 (see FIG. 10).
The press position circuits are shown with three-phase
primary excitation. This excitation may be any poly
phase number which would produce a rotating ?eld. The
rotating ?eld is shown on the rotor structure; the ?eld may
be applied to either the stator or the rotor in accordance
with the broader aspects of this invention. The output
of the synchroties SYl, 5Y2 and 5Y3 is shown as two
phase on both FIGS. 4A, 4B, 4C and 10; they could also
be single phase, three-phase, or any other polyphase out
to +A. This signal is of such an affect as to slow down
press drive DRll to bring its position back to the reference
put. The regulating components shown as magnetic am
pli?ers in FIGS. 4A, 4B, 4C and 10‘ may be Rototrol units
in accordance with the broader aspects of this invention.
position.
Since each of the three press signal arrangements are
Position reference units which have polyphase output other
identical, a study of drive DRE of PEG. 8 shows the affect
than two-phase may in accordance with the broader
of any unit being behind the average position. Referring 50 aspects of this invention be fed into a transformer arrange
to FIG. 8, c, the magnitude of voltage at +13 is propor
ment obtaining a two-phase voltage for obtaining and
tional to vector V31 and V32 and greater than the mag
measuring the position reference and position error quan
nitude of the voltage at +F which is proportional to
tities.
vectors V33 and V34. Since the voltage at +E is greater
In FIGS. 4A, 4B, and 40 the error signals are supplied
than the voltage at +F, current flows from E to F
through +A and +8, +C and +D, +E and +F. Since
through the regulator R3 which is in the opposite direc
these are all of positive polarities and are obtained from
tion to the ?ow obtained for drive DRl and is now in a
recti?ers it is necessary to use loading resistors between
direction such as to increase the speed of the third press.
Since the vectors V21 and V22, and V233 and V24 are
of the same magnitude the same potential exists at +C
and +D and no corrective action is required for drive
DRZ.
+A and Th5 and between +B and 105. In FIG. 10
the outputs of the position error circuit from both sides
of the push-pull arrangement are fed into separate wind
ings. A magnetic addition of ?ux occurs in the ampli?ers
By the use of the two-phase recti?ed power supplies for
MAT of FIG. 10 and the resulting ?ux developed by the
two windings supplies the error correction signal.
obtaining corrective signals to the drives a direct current
supply with much less ripple than would be obtained with
single phase recti?ed supplies is obtained. Filters are
necessary to ?lter the ripple voltage from the signal cur
rents to the drives DRl, DRZ, D113, but with the greatly
While a preferred embodiment of this invention has
been disclosed herein, many modi?cations thereof are
feasible. The invention, then, is not to be restricted ex
reduced ripple. By using the two-phase systems little
1. A control system for apparatus for treating work
cept insofar as is necessitated by the spirit of the prior art.
We claim as our invention:
70 progressively in a plurality of positions, said apparatus in
cluding means at each of said positions for treating said
The push-pull arrangement of obtaining signals for +A
work and drive means connected to each of said treating
and +3, +C and +D, and +E and +13, has an advantage
in that any regulation or change in magnitude of voltage
means for actuating said treating means, the said control
time delay is induced by the ?lters.
due to attenuation in adding and averaging reference
vectors or change in voltage due to rotational speed of
system including position regulating means connected to
each of said drive means for adjusting the position of the
3,078,402
17
associated drive means, means connected to each of said
drive means for deriving a signal dependent on the posi
tion of the associated drive means, means connected to
said signal deriving means of all of said drive means for
deriving a signal corresponding to the average of the
position dependent signals of all of said drive means,
means connected to each of said position dependent sig
nal deriving means and to said average signal deriving
means for deriving for each drive means a signal depend
ent on the‘ algebraic difference between said average sig
nal and the position dependent signal for the associated
drive- means, and means connected to each of said regu
18
of steps, the said apparatus including means at each of
said positions for treating said work and drive means con
nected to said treating means for actuating said treating
means, each of said steps consisting of a cycle during one
portion of which said work is treated and each said drive
means is subjected to a high load, said high load being
different for different drive means, and during the re
maining portion of which said work is advanced from
one said position to the succeeding said position, said
10 drive means being subjected to a low load during said
remaining portion, the said system comprising means con;
nected to all said drive means for continuously deriving
an average signal dependent of the average relative posi
lating means and to the associated difference signal deriv
ing means for causing said regulating means to set the
tion of all said drive means, means connected to each
associated drive means to the position corresponding to 15 said drive means and to said average signal producing
said average signal.
means for deriving for each drive means an error signal
2. In combination a ?rst drive shaft, a second drive
dependent on the deviation of said’ last-named drive
shaft, a third drive shaft, ?rst, second and third means
means from said average position, and means connected
connected to said ?rst, second and third shafts respec
to’ each said error signal deriving means and to each said
tively, for deriving ?rst, second and third signals depend~
drive means for continuously applying the associated
ent on the‘ respective positions of said ?rst, second and
said error signal to each said drive means to correct the
third shafts, means connected to said ?rst, second and
position of said last-named drive means so as to suppress
third means for deriving a signal dependent on the aver
age of said ?rst, second and third signals, ?rst, second
said error‘ signal.
'
6. In combination ?rst drive means, second drive
and third differential means connected to said average 25 means, means for producing a speed reference signal,
signal deriving means and to said ?rst, second and third
?rst means connected to said ?rst drive means and to
position signal deriving means for deriving ?rst, second
said signal‘ producing means responsive to said signal for
and third error signals dependent on the algebraic dif
ferences between said average signal and said ?rst, second
maintaining the speed of said‘ ?rst‘ drive means at a mag
nitude corresponding to said signal, second means con
nected to said second drive means and to said signal
and third position signals respectively, ?rst, second and
third regulators connected to said ?rst, second and third
shafts respectively for adjusting the positions of said
shafts, and ‘means connected to said ?rst, second and third
regulators for impressing on said regulators said ?rst,
producing means responsive to said signal for maintain
second and third error signals respectively to cause said
ing the speed of said second drive means at a magnitude
corresponding to said signal, ?rst means connected to said
?rst drive means, to said signal producing means and to
said ?rst and second signal responsive means for absorb
regulators to adjust their respective shafts so as to sup
ing a part of said signal external to said signal responsive
press the associated error signals.
means when the speed of said ?rst drive means is reduced
below a predetermined magnitude so that said ?rst and
3. A control system for apparatus for treating work
progressively in a plurality of positions, said apparatus
including means at each of said positions for treating said
Work and drive means connected to each of said treating
means for actuating said treating means, the said control
system including, means connected to each of said drive
means for deriving a signal dependent on the position of
the associated drive means, means connected to said sig
nal deriving means of all of said drive means for deriving
a signal corresponding to the average of the position
dependent signals of all of said drive means, means con
nected to each of said position dependent signal deriving
means and to said average signal deriving means for
deriving for each drive means a signal dependent on the
algebraic difference between said average signal and the
position dependent signal for the associated drive means,
second responsive means react with a signal correspond
ing to said last-named speed, and second means con
nected to said second drive means, to said signal produc
ing means and to said ?rst and second signal responsive
means for absorbing a part of said signal external to
said signal responsive means when the speed of said sec
ond drive means is reduced below a predetermined mag
nitude, so that said ?rst and second responsive means
react with a signal corresponding to said last-named speed.
7. In combination ?rst drive means, a ?rst tachometer
connected to said drive means for producing a ?rst poten
tial corresponding to the speed of said drive means, sec
ond drive means, a second tachometer connected to said
second drive means for producing a second potential cor
responding to the speed of said second drive means, ?rst
and means connected to each of said drive means and
recti?er means, second recti?er means, means producing
and third differential means connected to said average
pedance means, said second recti?er means and said sec
ond tachometer, with said second recti?er means con~
to the associated difference signal deriving means for 55 a speed reference potential, impedance means, means
setting the associated ‘drive means to the position cor
connecting in series said reference potential, producing
responding to said average signal.
means, said impedance means, said ?rst recti?er means
4. in combination ?rst, second and third drive shafts,
and said ?rst tachometer, with said ?rst recti?er means
means connected to said drive shafts for deriving a sig
poled to conduct under said reference potential and to
60
nal dependent on the average position of said drive shafts
block under said ?rst potential, means connecting in
referred to a starting position of said shafts, ?rst, second
series said reference potential producing means, said im
signal deriving means and to said ?rst, second and third
shafts respectively for deriving ?rst, second and third
nected to conduct under said reference potential and to
error signals respectively dependent on the algebraic de 65 block under said second potential, ?rst regulator means
viation of each of said shafts from its said starting posi
including a speed reference winding, a speed signal Wind
tion, and ?rst, second and third correcting means con
ing and an output winding, second regulating means in
nected to said ?rst, second and third shafts respectively
cluding a speed reference winding, a speed signal wind
and to said ?rst, second and third di?'erential means re 70 ing, and an output winding, means connecting in a ?rst
spectively, for correcting the positions of said ?rst, sec
series circuit said speed reference potential producing
means, said impedance means, and said speed reference
signal.
winding of said ?rst regulator means, means connecting
5. A control system for apparatus for treating worlc
in a second series circuit said speed reference potential
progressively in a plurality of positions during a plurality 75 producing means, said impedance means, and said speed
ond and third shafts so as to suppress its associated error
3,078,402
19
255i
reference Winding of said second regulator, means con
necting in a third series circuit said ?rst tachometer and
?rst, second and third differential means respectively, for
correcting the positions of said ?rst, second and third
said speed signal winding of said ?rst regulator means,
shafts so as to suppress its associated error signal while
means connecting in a fourth series circuit said second
increasing the speeds of said shafts to said predetermined
tachometer and said speed signal winding of said second
regulator means, the ampere turns through said speed
reference windings in said ?rst and second circuits coun
speed.
9. In combination ?rst drive means, second drive
means, means for producing a speed reference signal,
?rst means connected to said ?rst drive means and to said
teracting the ampere turns through said speed signal
windings in said third and fourth circuits respectively,
signal producing means responsive to said signal for
means connecting said output winding of said ?rst reg 10 maintaining the speed of said ?rst drive means at a mag
ulator to said ?rst drive means in regulating relation
ship therewith, and means connecting said output wind
nitude corresponding to said signal, second means con
nected to said second drive means and to said signal
ing of said second regulator to said second drive means
producing means responsive to said signal for maintain
in controlling relationship therewith.
ing the seed of said second drive means at a magnitude
corresponding to said signal, and means connected to
said ?rst drive means, to said signal producing means
8. In combination ?rst, second and third drive shafts,
speed regulating means connected to said'drive shafts
for maintaining said shafts at a predetermined spee
when all said shafts have a speed not loaded substantially
lower than said speed and for permitting all said shafts
to drop to a lower speed when at least one of said shafts
drops substantially below said predetermined speed,
means connected to said drive shafts for deriving a sig
nal dependent on the average position of said drive shafts
referred to a starting position of said shafts, ?rst, second
and third differential means connected to said average sig
nal deriving means and to said ?rst, second and third
shafts respectively for deriving ?rst, second and third er
ror signals respectively dependent on the algebraic devia
tion of each of said shafts from its said starting position
when said shafts are operating at said lower speeds, and 30
?rst, second and third correcting means connected to
said ?rst, second and third shafts respectively and to said
and to said ?rst signal responsive means for absorbing
a part of said signal external to said signal responsive
means when the speed of said ?rst drive means is reduced
below a predetermined magnitude so that said first and
second responsive means react with a signal correspond
ing to said last-named speed.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,451,946
2,883,036
Harris _______________ __ Oct. ‘19', 1948
Fox et al. __________ __ _ Apr. 21, 1959
2,885,616
Anger et a1 ____________ __ May 5, 1959
145,963
707,138
Australia _____________ __ Apr. 2, 1952
Great Britain _________ __ Apr. 14, 1954
FOREIGN PATENTS
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