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Патент USA US2405718

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Aug. 13, 1946.
R. A. SCHAFER
2,405,718
'
MACHINE TOOL
Filed May 5, 1944
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MACHINE TOOL
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MACHINE TOOL
Filed May 5, I944
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Patented Aug. 13, 1946
2,405,718
UNITED STATES PATENT OFFICE
2,405,718
MACHINE TOOL
Robert A. Schafer, Richmond, Ind., assignor to
National Automatic Tool Company, Inc., Rich'
mond, Ind., a corporation of Indiana
Application May 5, 1944, Serial No. 534,220
11 Claims. (Cl. 10-129)
1
2
My invention relates generally to machine tools,
and more particularly to improved mechanical
A further object is to provide a machine tool
for the performance of tapping operations, with
improved combined electrical and mechanical
spindle driving motor control means.
Other objects will appear from the following
description, reference being had to the accom
and electrical control means for machine tools
used for tapping operations.
It has been common practice to provide ma
chine tools with suitable controls for causing a
spindle driving motor to reverse at the end of
a forward portion tapping cycle and to stop after
panying drawings, in which:
Fig. 1 is a front elevational viewof the machine
the tap has been withdrawn from the work. Such
machines have usually included a rotary limit
switch, geared to the tap carrying spindle, which
tool;
could be set to cause reversal of the spindle driv
ing motor and application of a brake thereto
upon completion of a predetermined number of
revolutions of the spindle, and to cause the motor
to stop after it had driven the spindle in the
reverse direction an equal number of revolutions.
Due to the momentum, particularly of the
tional view showing the spindle drive gearing;
Fig. 2 is a left side elevational View thereof;
Fig. *3 is an enlarged fragmentary vertical sec
Fig. 4 is a transverse sectional View, taken on
the line ll—4 of Fig. 5, with the rotation switch‘
> cover plate removed;
‘
,
Fig. 5 is a fragmentary vertical sectional view
showingthe safety clutch and a portion of the
spindle drive gearing, and taken on the line 5-5
of Fig. '7;
, I
rotating parts of the motor, such limit switch
necessarily had to operate with a high degree of 20 Fig. 6 is a side elevational view of the limit
switch and clutch operating mechanism, taken on
precision and reliability, to prevent tapping to a
the line 6-6 of Fig. 5;
greater depth than desired. Since in many pieces
Fig. 7 is a fragmentary transverse sectional
of work the tapping operation required that the '
view, taken. on the line 'I—'| of Fig. 5;
tap substantially bottom in the hole, slight ‘over
Fig. 8 is a simpli?ed schematic wiring diagram
running of the tap often resulted in breaking the
of the electrical control circuits; and
taper damaging the work. Under ordinary cir
Fig. 9 is a schematic wiring diagram of the
cumstances such limit switch controlled tapping
electrical control and power circuits.
machines would operate properly, but occasion
ally, after some use, either the limit switch or
the solenoid brake on the motor failed to operate
properly, and the resulting undesirable over
'
The invention is illustrated as embodied in a
machine tool comprising a base 52 (Figs'l and 2) ,
a vertical column 53, and a tapping unit head 55%
running of the tap occurred sufficiently fre
quently to render thistype of control not entirely
satisfactory.
'
.p
General description
adjustably secured to the column 53. The tap
-
Various other expedients, such as mechanically
” ping unit comprises one or more spindles 55
operated snap-acting clutches, have similarly
carrying taps 58 and driven by a. motor 60
through gearing contained in a gear box 62, and
been found subject to failure, resulting in over
running of the taps.
It is therefore an object of myinvention to
through a clutch mechanism contained in a cas
ing 64. Suitably mounted on the base 52 is a push
provide a, tapping machine with improved safety ' - button panel 66 having a forward push button
means for controlling the operation of the spindle
driving motor, which is positive in operation, and
which will preclude over-running of the taps.
A further object is to provide an improved
68, a reverse push button 10, and a selector push
button 12. Suitably mounted at the rear of the
vertical column 53 is a cabinet ‘M containing
various relays and electrical control circuit ele
machine tool for performing tapping operations,
in which the operation of the spindle driving mo-.
tor is electrically controlled, and in which safety
mechanical clutch means are provided to' pre
vent over-running of the tap carrying spindles in
the event of failure of the electrical reversing
system, or failure of the solenoid operated brake
on the motor.
.
~
.
‘
ments,
As best shown in Fig. 5, the driving shaft of
the motor 60 is connected to a shaft extension
16 by a coupling 18, the shaft 16 being sur
rounded by a spacing sleeve 80 and mounted for
rotation in anti-friction bearing assemblies 8|v
and 82, The shaft extension 16 is splined to
receive a pinion 84 which meshes with a gear
86. The gear 86 is formed integrally with a'hub
,A further object is to- provide an improved
control means for a machine tool used in the
sleeve 88 mounted for rotation in anti-friction’
performance-of tapping operations.
~ 1 55 bearing assemblies 89 and 90. The gear 86 has
same
3
4
jaws £32 formed on its upper hub for engage
ment with complementary jaws 94 formed on
a clutch member 95, the member 96 being suit
cam I78, and a reverse cam I80 are adjustably
secured to the cam disc I72, being non-rotatably
clamped thereto by means of a nut I82. The
ably splined or keyed to a shaft 93 so as to be
cam I 89 is adapted to engage a roller on the
actuating arm I84 of a reverse limit switch
RLS—FI , while the cam I74 is adapted to engage
the roller on the end of the actuating arm I86
of a rotary limit or stop switch RLS_RI.
The cams I16 ‘and H8 are in alignment with
a roller I88 carried by a clutch latch bellcrank
I50. The latch I90 is pivoted on a stud I92 and
has a portion I94 engageable in a notch I96
formed in a bifurcated clutch lever I918. The
longitudinally slidable thereon. The clutch
member at is provided with an annular groove
I?il to receive a pair of roller carrying pins I02
secured to a clutch operating yoke I04 (Fig. '7),
the latter being secured to a shaft IE5.
Suitably splined to the lower end of the shaft
10
Q8 is a main drive pinion I88 (Fig. 5). As best’ '
shown in Fig. 3, the pinion I03 meshes with'a
gear H0 carried by a countershaft H2 suitably
mounted for rotation in the gear look ‘62. A pine‘
ion IIIl secured to the shaft H2 meshes‘with
gears H6, each non-rotatably secured to a spin
is
portion I94 of the clutch latch is held in engage
ment in the notch I 96 of the clutch lever by a
‘compression coil spring 2% mounted in suitable
dle drive shaft H8. The spindle drive -~sh~afts 7
H8 are suitably mounted in bearings formedjinj I
the gear box 62. Each of the spindle shafts H8
has a slip coupling member I23 formed at the 20
lower en'dthereof to receive the splined end I22
of .a lead screw I24. The lead screw i211! ‘is
threaded in a lead ‘screw nut I26 and may be
formed integrally withthe tool receiving spindle
I28. Resting upon the nut 12%, andnon-‘rot'at
sockets formed in the latch I 90, and in the upper
‘arm of. the clutch lever I88. The clutch lever
I98 is non-rotatably secured to the shaft I06 to
which, it will be recalled, the clutch operating
yoke I04 is secured. Thus, counterclockwise
movement (Fig. 6) of the clutch lever I 38 will
cause disengagement of the jaw clutch '92, 94,
and thereby disengage the gear 88 from the shaft
93, and interrupt the drive to the. spindles.
When the spindles are being driven in the for
ward direction, the clutch disc 112 (Fig. 6) ro
tates counterclockwise and ‘such rotation will
ably interlocked therewith, is a washer I29 hav
ing sidewardly extending lugs 133 which are
guided in slots I32 formed in a spindle sleeve I34,
continue until the cam I85 ‘engages the roller
The nut I25 is not rotatable in the sleeve I34,
but is capable of limited movement longitudinally 30 on the operating arm I84 of the reverse limit
thereof. Suitable bearing bushings I36 and I 38
switch RLS-FI, whereupon, as will hereinafter
are secured in the sleeve in: for rotatably sup
appear, the connections to the motor 50 will be
porting the spindle. The sleeve I35 has ‘an an
changed to cause it to reverse its direction of
nularly ‘grooved enlarged lower end portion I40
rotation. If, however, the switch RLS-FI fails
which is detachably secured‘against'the lower
to operate, the continued counterclockwise move
end of the spindle box by means of a‘ suitable
ment of the cam disc I72 will cause the cam I18
clamp I112. The sleeve It'i'may be provided with
.to engage the roller I88 of the clutch latch ‘I90
a depending oil guard ‘skirt portion'llid. j '
and swing the latter clockwise to disengage its
latch portion I 9ll'from the notch "I95. 'Due to
Thus, as the spindle shaft H8 rotates, the *lead
screw 124 feeds downwardly through the nut I26 40 the action of the spring 20s, the clutch lever I98
and advances ‘the tap into‘ the work- In the
will thus be swung counterclockwise, and thereby
event. that, prior to enteringv the, hole to be
raise the yoke pins I62 (Fig. 5) and disengage
tappedthe tap meets an obstruction preventing
the jaw clutch member 96 from the jaws 92 on
its downward ‘movement (as'might be the case if,
the hub of the gear 85. If the spring 239 is not
due to some error; the'workpiecewas not prop
sufficiently powerful to cause such clutch disen
erly drilled for the hole to be tapped), the nut
gagement, the adjacent portioncf the clutch
12% may travel upwardly on the lead screw
latch I9!) will engage the upper arm of the clutch
against the force applied by "a spring I 45, and
lever Hi8 and forcibly disengage the clutch.
thus prevent breakage of the tap. The coil spring
In a similar manner, upon completion of'the
I45 is compressed between the bushing I35 and
required number ‘of reverse revolutions 'of'the
the washer I 29 resting upon the upper end of
taps,‘ the stop cam I74 will ‘engage the roller ‘on
the nut I25, and maintains sufficient ‘downward
the ‘actuating arm I85 of the rotary limitswitch
pressure on the tap to cause it to engage ‘and
RLSe-RI to cause deenergization ‘of the spindle
feed into the work.
Upon reverse rotation of
the spindle shaft I22, the lead vscrew will feed
upwardly through the nut I26, and thus when
the tap has been completely withdrawn from the
work, the nut will have returned to the position
in which it is shown in Fig. 3.
.
55
tor contin'ues'to coast to an undesirable extent,
the cam I16 will engage the roller I88 and there
.
Clutch disengaging mechanism _
driving motor 60. If, however, through some ‘fail
me of the switch RLS-RI, "or through ‘failure of
the plugging circuit to operate properly, theme
by swing the clutch latch, I 96 clockwise to cause
60 the latch portion I94 thereofto be removed from
A pinion I50 (Figs. 5 and '7) is nonerotata'bly
secured to the shaft 98 and meshes with a ‘gear
the notch I96 and thus effect ‘counterclockwise
swinging movement of the bifurcated clutch lever
I98 ‘to cause disengagement ‘of the clutch 92, 94,
and thereby disconnect the driving motor ~65
I52 secured to a shaft I515; The shaft I55 ‘car
ries a worm I56 meshing with a worm gear I58. 65 from the tap carrying spindles. Since the mo
mentum of the, spindles is relatively slight 4com~
The worm gear IE8 is secured to a shaft I66
mounted in suitable anti-friction bearings I52,
I63, ‘and having a gear I54 at its right-hand end
(Fig. '7). The gear I54 meshes with a pair of
idler pinions I85, I67, which are mounted for 70
free rotation on stationary pins I88, the idler
pinions I65, I 61 meshing with an internal gear
pared to vthe frictional torque ‘load retarding
movement’ thereof, the spindles will piomptly
come to rest, while the mot-or 56!} may (continue to
coast harmlessly,
_
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>
If the ‘operator finds that the motor continues
running after the jaw clutch 92, 96 isdise'ngaged,
it will indicate that the reverse limit ‘switch
. RLSQFI has railed to operate and requires re
clutch disengaging cam 1T6, a ‘clutch over-travel 75 pair or replacement. ' Similarly, if "the motor fails
Il'EI formed integrally with a cam disc I12.
As best shown in Fig. 6,- a stop cam IM, a
"2,405,718
K
5.
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of the CRl contact between conductor C3 and
conductor It results in energization of CRFl.
to stop after completion of the return portion of
the cycle, it will indicate to the operator that the
stop switch RLS—R! has failed to operate and
The relay CRFI is looked as soon as the motor
starts forward, by means of ‘rotation switch RE.
which completes a ‘circuit from conductor 03,
correction of. this condition is required.
After an occurrence of disengagement of the
switch RSF, conductor 26, and winding of CR4‘
to conductor Cl. Energization of CR4 resultsin
closure of the CR4 contacts between conductors
jaw clutch 92, 94, the operator will be required
to reposition the clutch latch, clutch lever, and
jaw clutch members in latching and clutch en
gaging position. To accomplish this, there is pro
C3 and Cl 3.
Since the CRFl contacts between
vided a stub shaft 202 having a squared end por 10 conductors l3 and I4, are closed, a locking circuit
is thus established for the winding of CRFl.
tion 204 for engagement by a suitable crank-like
Energization of relay CRl also closes the CRl
tool. The shaft 282 has a notched coupling ele
ment 206 at its lower end, the notches thereof
being engageable with the ends of a pin 298 which
extends diametrically through the upper end of '
the shaft 93. The shaft 202 is normally held in
its upper position by a compression coil spring
2l0 with the coupling 296 free from the pin 26%.
When it is necessary to reset the clutch latching
elements, the operator applies a crank to the 20
upper end of the shaft 282 and presses the shaft
downwardly to cause engagement of the coupling
member 286 with the pin 258, and then rotates
the shaft 98 in such direction as will cause the
cam members I'M, H8,’ H8, and Hill to be ro
tated to their normal positions, such as shown,
for example, in Fig. 6.
When the ‘cams H4, H6, H8, and lSEl have
thus been rotated to normal position, a suitable
contacts between conductors II and I2, and ener
gization of CRFI closes its contacts between con
ductors l2 and'l3. A circuit through the relay Fl
is thus completed, this circuit being traced as fol
lows: Conductor C3, CRl contacts, conductor l4,
CRFI contacts, conductor l3, CRF! contacts, con
ductor l2, CRl contacts, conductor l l, reverse
push button switch ll}, conductor ' l, RLS-—Fl
contacts, conductor I5, winding Fl, to conductor
C I .
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I i
Energization of Fl results in starting the motor
6!! in a forward direction. The motor will run in
a forward direction until the forward push button
68 is released, thus deenergizing CRl, or until the
limit switch RLS'—Fl opens the contacts between
conductors ‘l and 15 at the forward limit. Open
ing the latter contacts, or deenergizing the relay
crank or wrench is applied to the squared end of _ . CRl will, of course, result in deenergization of Fl
shaft I06. By rotating shaft I86 clockwise (Fig.
6), the clutch member 96 will be moved down
wardly to reengage its jaws 94 with jaws 92, and
the clutch operating lever I98 will be swung
clockwise again-st the force of the spring 20!} until
the plate lei; of the latch i911 reengages in the
notch I96. It will be apparent that in order to
reengage the clutch in this manner, the move
ment of the roller I88 must not be impeded by
either the cam H6 or cam l‘lll.
A pulley 22B is non-rotatably secured to the
upper end of the worm shaft led and is provid
ed with a belt 222 for the operation of a rota
tion plugging switch RS, this switch being of
conventional construction and operating to close
and thus interrupt the current supply to the mo
tor 6E.
,
Control relay CR4 remains energized as long as
the motor Bl! continues to rotate or coast forward,
1 thus maintaining the, holding circuit for CRFl
until forward rotation of the motor ceases.
Whenrelay Fl is deenergized, it closes its con
tacts between conductors 22 andsl, Thus a cir
cuit BI is completed from the conductor C3, con~.
' tacts of CR4, conductor l3, closed contacts of
CRFl, conductor 20, closed contacts of CRI, con~
ductor 2i, closed ‘contacts of CR6, conductor 222,
closed contacts of Fl, conductor l, closed contacts
of RLS—R|, conductor l8, and winding‘arm of
RI ,‘ to conductor Cl.
'
switch contacts RSF (Figs. 8 and 9) when the
spindle is being driven in a forward direction,
and to close switch contacts RSR ‘when the
spindle is being driven in a reverse direction.
to the motor 69 to cause it to rotate in the reverse
This switch mechanism operates promptly after
any change in the direction of rotation of the
rotating in the reverse direction. As soon as the
shaft 98, since the belt 222 is in ?rm frictional
engagement with the pulley 228 and the switch
mechanism has but little lost motion.
Control circuits .
Energization of RI results in applying power
direction. This application of reverse torque to
the motor causes it to stop quickly and commence
motor starts rotating in the reverse direction, it
opens the rotation switch contacts RSF, and closes
contacts RSR, thus deenergizing CR4 and ener
gizing CR5. Deenergization of CR4 opens its con
tacts between conductors H and 22, which opens
the previously described energizing circuit for RI.
This will occur promptly after the reversal of the
motor. The motor will stop rather promptly due
The control circuits for the machine are 11
lustrated in simpli?ed form in Fig. 8, and in
to friction, the extent of re'vcrserotation depend
more complete form in Fig. 9. Referring to these
?gures, a transformer 2l2 has its primary windm 60 ing upon the length of time it takes CR4 to open _
and upon the amount of friction in the machine.
ing connected to line conductors Ll and L3, and
To cause the motor to operate in the reverse di
its secondary winding being connected to con
rection, the reverse Push button 10 is depressed
trol conductors CI and C3. When the machine
and this results in reverse rotation of the motor
is to be manually controlled, the push button op
in a manner similar to that described above with.
erated selector switch 72 is in its upper position,
reference to forward rotation.
- V
connecting conductor C3 to conductor 5. The
More specifically, operation of the reverse push
motor 66 may then be jogged in a forward or re
button ‘it! vcompletes a circuit from the conductor
verse direction by pressing the push button 58
C3 through the selector switch ‘l2 (the latter
or the push button ‘H3.
'
being in its ‘upper position, Fig. 8), conductor 5',
When the push button 88 is operated, the con
reverse'switch ‘l0, conductor IE, to energize relay
ductor 5 is connected to the conductor 6 and
thereby completes a circuit through the winding
CR2. Thus the contacts CR2 between conductors
of control relay CR! to the return conductor Cl.
C3 and l? are closed, and relay CRRI is energized.
Energization of relay CRl operates, the contacts
The contacts CRRI between conductors 4 and I'll
bearing the reference character CR'l. Closure‘ 75 are thus closed, and a circuit for energiz'ation of
2,405,7'1g
7.
.
the relay R! is completed as follows: From con
ductor C3, contacts CR2, conductor !‘I, contacts
CRRI, conductor 4, contacts CRRI, conductor 3,
contacts CR2, conductor 2, push button switch 58.
(in its upper position), conductor l, contacts 5
tinues rotating forwardly until the forward limit
switch RLS—F! is opened, thereby opening its
contacts between conductors '! and !5, where
RLS-Rl, and winding of relay R! to conductor 7
Cl.
‘
Energization of relay R! causes operation of the
8'
gizing, CR4. Closure of contacts CR4 ‘connects
conductor C3 to conductor !3, and, through con
tacts CRF! and conductor !4, establishes a hold
ing circuit for relay‘CRFl. The motor thus con
‘ upon the supply of ‘current to the motor '60 is
interrupted by deenergization of relay Fl.
contacts shown above it in Fig. 9, thereby chang
It
ing the connections to the motor 60 to cause it to 10 will be noted that upon energization of CR3, con
rotate in the reverse direction. As soon as such
ductors !! and i2 are connected by the CR3 con
tacts so that when the forward push button 68
reverse ‘rotation has commenced, the rotation
is released and CR! deenergized, the holding‘cir
switch contacts RSR are closed, and relay CR5
thereby energized, establishing a connection be
cuit for relay F! will remain established.
‘
When RLS-F! is operated, its lower’contacts
tween conductors C3 and 4. The motor will 15
between conductors 25 and !6 are closed, thereby
therefore continue rotating‘ in the reverse direc
establishing a circuit through CR2. The conse
tion until the push button 16 is released, or the ro
quent energization of CR2 results in the energiza
tary limit switchRLS-Rlis opened due to the
tion of CRR! through the following circuit: con
return of the taps tovtheir starting or normal po
ductor C3, contacts CR2, conductor !l, relay
sition'. Such, opening of the RLS--R! contacts
CRRI, and conductor CI. Energization of CRR!
between conductors ! and !8 deenergizes relay RE
through closure of its contacts results in the en
and temporarily energizes relay F! through a cir
ergization of R! to cause the application of a
cuit traced as follows: conductor C3, contacts
plugging torque to the motor 60, this being accom
CR2, conductor !l, contacts CRRI, conductor 4,
‘contacts CRRI, conductor 8, contacts CR2, con 25 plished through the following circuit: conductor
C3, contacts CR2, conductor ill, contacts CRR!,
conductor 4,. contacts CRRI, conductor 3, con
tacts CR2, conductor 2, push button switch 68,
conductor !, limit switch RLS—R!, conductor It’,
ductor-9, contacts CR5, conductor !0, contacts RI,
conductor 1, upper contacts of RLS-Fl, and re_
lay F! to conductor CI. The relay F! will oper
ate. the motor control contacts so as to connect
the motor 80 to the line conductors Ll, L2, and 30 and relay R! of conductor Ci. As soon as the
L3, in a manner to cause forward rotation of the
motor. The application of current to the motor
in the forward direction applies a braking or plug
ging torque to the motor so that it stops its re
verse rotation rapidly and commences rotating 35
motor has been stopped and commences reverse
rotation, the rotation switch contacts'RSR are
closed, thereby energizing CR5. Energization of
CR5 results in locking (JR-R! in energized con
dition until reverse rotation stops, through the fol
lowing circuit: from conductor C3, contacts CR5,
conductor 5, contacts CRRI, conductor I7, and
relay CRRI, to conductor CI. The motor will
forwardly. Upon initial forward movement of the
motor, the rotation- switch contacts RSR will be
opened, thus deenergizing CR5 and opening the
contacts CR5 between conductors "9 and I0, there
therefore run in reverse direction until limit
by deenergizing relay Fl . and bringing the motor 40 ‘switch RLS—R! is opened, thereby deenergizing
relay R! and interrupting the supply of current
.to a stop.
to the motor 60.
It will be understood that the tapping head unit
When relay R! is deenergizecl, its contacts be
54 may form part of .a single head'machine either
tween conductors i0 and l are closed,‘ and this’
of the vertical or horizontal type, or may be at
any desired angle relative to the vertical, and that 45 results in energization of relay F! through the
following circuit: conductor C3, contacts CR5,
conductor 4, contacts CRRI, conductor 8, contacts
it may form part of a multiple unit machine si
multaneously or successively performing a multi
plicity of machine operations upon the work. In
such multi-unit machines particularly, it is de
CR2, conductor 9, contacts CR5, conductor !0,
contacts RI, conductor' ‘1, upper contacts of
RLS-Fl, conductor !5, relay F1, to conductor
Ci. Energization of relay F! resultsin the ap
sirable to provide for automatic tapping cycles.
In the machine illustrated, this is accomplished
by operating the selector push button E2 to its
automatic cycle position, that is, closing the
switch between conductors C3 and 25. Closure of
this switch results in energization of CR3. The
automatic cycle is started by pressing the forward
push button 68, thereby energizing CR! through
the following circuit: conductor C3, selector
switch 72, conductor 25, contacts CR3, conductor
plication of power to the motor (it! to apply a for
ward torque thereto, thus bringing the motor to
rest and starting it in a forward direction. Upon
y
1)
initial forward rotation of the motor, the rotary
switch contacts RSR are opened, thereby deene‘r
gizing relay CR5, and immediately thereafter
closing rotation switch contacts RSF to energize
CRIS; When CR5 is deenergized, it opens its con
CRI, conductor !4, CRFI, and Cl. Energization
tacts between conductors 9 and I6, breaking the
energizing circuit for relay F!, and thus cutting
off the supply of power to the motor 60. The
motor therefore coasts forward to rest, complet
ing an automatic cycle.
of CRFicompletes a. circuit to energize F! as
Operation
5, push button switch 68, conductor 5, CR! , to
conductor Cl.
‘Energizatioh of CR! completes a circuit to ener
gize CRF! as follows: conductor C3, contacts
follows: conductor C3, contacts CRl, conductor
!4, contacts CRFI, conductor !3, contacts CRF!,
conductor !2, contacts CRI, conductor ll, con
tacts of reverse switch ‘!5 (in itsalupper position).
conductor 7, upper contacts/pf RLS—VFi, con
ductor !5, relay FI, and conductor Cl. Relay Fi
causes the current to be suppliedto the motor E8
in a. manner to,cause forward rotation thereof.
As soon as the motor starts in a ‘forward direction,
the rotation switch contacts ‘RSF are closed, ener
The details of the operation of the machine.
have been set forth above in connection with the
description of the control circuits. It is therefore
necessary at this time merely to give a résumé of
the general principles of the operation of the ma
chine.
By means of the selector push button switch 12,
the controls of the machine may be conditioned,
75 either for independent push button control or for
"2,405,718
9.
10'
‘automatic cycling. When the selector switch 12
is in position for independent control, the op
to operate promptly to reverse or stop the opera
erator is enabled tojog the machine forward or
reverse at any point in its travel between the
limits set by the cams I'M and I 83, which operate
the limit switches RLS—RI and RLS-Fl'. Such
?exibility of control is desirable in setting up the
machine. Each time the spindle driving motor is
stopped, whether it has been rotating in a forward
or reverse direction, current is supplied to the 10
motor in a manner to apply a braking or plug
ging torque thereto, thus overcoming the dim
tion of said motor. '
'
'2. In a machine tool for performing tapping
operations, the combination of a driving motor, a
tap carrying spindle, gearing connecting said
motor to said spindle, said gearing including a
clutch mechanism for severing the driving con
nection between said motor and said spindle, a
control circuit including limit switch means oper
able to cause reversal of the direction, of rotation
of said motor upon completion of a predeter
mined number of revolutions of said spindle in a
culties inherent in the variable coasting of the.
forward direction and after said spindle has been
motor to a stop. -This application of electro
magnetically applying‘reverse torque to the motor ,
in order to stop it will operate in every case ex‘
cept in the event of power failure. Under the lat
rotated in a reverse direction through said pre
ter unusual condition, the motor Will‘merely coast
to a stop.
'
‘
If for any reason either of the rotary limit
switches RLS-Fl, RLS—RI, should fail to oper
ate properly, the clutch release mechanism will
determined number of revolutions, and means to
cause disengagement of said clutch mechanism
uponv substantial over-travel of said spindle‘.
3. In a machine tool for performing tapping
operations, the combination of a driving motor,
a tap carrying spindle, a gear train including a
clutch forming a driving connection between
said motor and said spindle, electrical meansfor
be tripped by the cam H6, or the cam I18, and
controlling the application of power to said mo
the spindles will come to rest quickly while the
tor, said means including two limit'switches, a
motor 60 may coast freely to a stop.~ After the 25 cam plate, means for driving said cam plate with
clutch 92, 84 has been disengaged, it is neces
‘said spindle, a plurality of cams adjustably se
sary for the operator to reset the clutch manual
cured to said cam plate for respectively operat
15'. The fact' that it requires some effort upon
ing said limit switches, means for operating said
the part of the operator to reset the clutch will
clutch to cause disengagement thereof, and. a ‘
usually induce the operator to see that the fault 30 pair of cams adjustably secured to. said cam
which caused the clutch disengagement is
plate and arranged to operate said clutch disen
promptly corrected. The resetting of the clutch
gaging means upon failure of either of said limit
requires that the operator apply a crank to the
switchesto stop the operation of the motor when
end of the shaft 202 and rotate the spindles
such limit switch is'operatively engaged by its
back to operative position, and then effect re
associated cam.v
’ '
engagement of the clutch and repositioning of
4. In a machine tool for performing tapping
the'clutch latching mechanism.
operations, the ‘combination of a driving motor,
From the foregoing, it will appear that the
a'tap carrying'spin'dle, a gear train including a
invention provides a simple and effective means
clutch forming a driving connection between said
for positively preventing over-travel of the spin Ill) motor and said spindle, electrical means for con
trolling the application of power'to said motor,
dles in either direction, and thus affords ade
quate protection against damage to work and
said means including a limit switch, a camplate,
rme'an's‘for driving said cam plate with said spin
tools-which might otherwise result from such
dle, a cam'adjustably secured to said cam plate
over-travel.
I .
‘
While I have shown and described a particular 45 for'operating said limit switch, means for oper
ating'said ‘clutch to cause disengagement thereof,
embodiment of my invention, it will be appa
and a cam adjustably secured to said c'am plate
rent that numerous variations and modifications
and arranged to operate said clutch disengaging
thereof may be made without departing from the
underlying principles of the invention. I there
means upon failure of said limit switch to stop
fore desire, by the following c1aims,'to include 50 the operation of the motor when said limit
switch is operatively engaged by said cam.
within the scope of my invention all such varia
5. In a machine tool for performing tapping
tions and modi?cations by which substantially
operations, the’combination of a driving motor,
the results of my invention may be obtained
a tap carrying spindle, a gear train including a
through the use of substantially the same or
clutch forming a driving connection between said
equivalent means.
motor and said spindle, electrical means for con
I claim:
trolling the application of power to said motor,
1. In a machine tool for performing tapping
operations, the combination of a driving motor, a '
said means including a limit switch, a cam for
tap‘ carrying spindle, gearing connecting said
operating said limit switch, means for driving
clutch mechanism for severing the driving con
nection between said motor and said spindle, a
limit switch operable to cause reversal'of the
direction of rotation of said motor upon comple
tion of a predetermined number of revolutions of
said spindle in a forward direction, a second limit
said latching means to cause disengagement of
saidclutch upon failure of said limit switch to
stop the operation of the motor when said limit
switch is operatively engaged by said cam.
6. In a machine tool for performing tapping
operations, the combination of a driving motor,
a tap carrying spindle, a positive mechanical
clutch and gearing forming a driving connection
said cam with said spindle, latching means hold
motor to said spindle, said gearing including a 60 ing said clutch engaged, and means for tripping
switch operable to stop the operation of said
motor after said spindle has been rotated in a
reverse direction through said lpredetermined
number of revolutions, and means to operate said
clutch mechanism to sever the driving connec»
tion between said motor and said spindle in the
event of substantial over-travel of said spindle
due to failure of either of said limit switches
between said motor and said spindle, cam means
geared to said spindle, limit switches respectively
operable by said cam means at the ends of the
forward and reverse rotation of said spindle, con_
trol circuits rendered effective by the operation
of said limit switches tov cause application of
'2,405,7I8
11
power to said motor in a manner to provide a
braking torque thereto to cause the motor rapidly
to come torestand to commence rotation in the
opposite-direction, and a rotation switch mecha
nism responsive to the direction of rotation ‘of
said motor to interrupt the supply ‘of braking
torque current to said motor promptlyuafter it
has changed its direction of rotation.
7. In a machine tool for performing tapping
operations, the combination of a driving motor,
a tap carrying spindle, apositive mechanical
clutch and gearing forming a driving connection
9. In a machine tool for performing tapping
operations, the combination of a driving motor,
a tap carrying spindle including an individual
lead screw, a gear train including a clutch form
ing a driving connection between said motor and
said spindle, electrical means for controlling the
application of power to said motor, said means
including a limit switch, limit switch operating
means geared to said spindle, and means geared
to said spindle for operating said clutch to cause
disengagement thereof, said last named means
operating only upon failure ‘of said limit switch
to stop the operation of'the motor promptly after
geared to said spindle, limit switches respectively
operation of the limit switch.
10. In a machine tool for performing‘ tapping
operable by said cam means at. the ends of the 15
operations, the combination of a driving motor,
forward and reverse rotation of said spindle, con
a tap carrying spindle, a gear train including a
trol circuits rendered e?ective by the operation
of said limit switches to cause application of
‘clutch forming a driving connection between said
between said motor and said spindle, cam means
power to said motor in a manner to provide, a
motor and said spindle, electrical means for con
braking torque thereto to cause the motor rapidly 20 trolling the application of power to said 'rnotor,
said means including two limit switches, a cam
to come to rest and to commence rotation in
support, means for moving said cam support at
the opposite direction, a rotation switch mecha
nism responsive to the direction of rotation of
a speed and to an extent proportional to the rota
said motor to interrupt the supply of braking
tion of said spindle, a plurality of‘ cams adjust
torque current to said‘ motor promptly after it 25 ably secured to said support for respectively oper
ating said limit switches, means for operating
has changed its direction of rotationfand‘means
to disengage said clutch upon failure of said'mo
said‘ clutch to cause disengagement thereof, and
tor to come to rest promptly after the'operative
means adjustabiy secured to said' support and
arranged to operate said clutchv disengaging
engagement of said cam means and one of ‘saidv
limit switches.
'
a
30 means upon failure of either of said limit switches
8. In a machine tool for performing tapping
‘to stop the operation of the motor when such
operations, the combination of a driving‘m'otor,
limit switch is operatively engaged by its asso
a tap carrying'spindle, a gear' train including a
ciated cam.
'
'
clutch forming a driving connectionv between
11. In a machine tool for performing tapping
said motor and said spindle, electricallmeans'for
operations, the combination of a driving ‘motor,
controlling the application of‘p'ower to said mo
a tap carrying spindle, gearing connecting said
tor, said'means including a limit switch, a cam
motor to said spindle, said gearing including a
for operating said' limit switch, means for driv
clutch mechanism for severing the driving con
ing said cam with said‘ spindle, latching means
nection between said motor and said spindle, a
holding said clutch engaged, means for tripping ~10 control circuit including limitswitch means oper
said latching means to cause disengagement ‘of
able to stop said motor upon completion of a
said clutch upon failure of said limit switch to ‘
predetermined number of" revolutions of said
stop the operation’ of the motor when‘ said limit
spindle in a forward direction, and means to cause ~
switch is operatively engaged by'said cam, and
disengagement of said clutch mechanismfupon
manually operable means to' rotate said spindle ‘substantial’ over-travel of said spindle. '
toa position in which said clutch latching means
may be reset.
~
’
ROBERT A. SCHAFER, V
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