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Патент USA US2405474

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Aug. 6, 1946.
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T. c. VAN DEGRIFT
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BALANCING
MACHINE
Filed Nov. 27, 1942
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2,405,474 ,
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2 Sheets-“Sheet 1
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Summon:
Aug- 65 1946-
'rQc. VAN DEGRIF‘T
2,405,474
BALANCING MACHINE
Filed Nov. 27, 1942
513
2 Sheets-Sheet 2
Patented Aug. 6, 1946
v 2,405,474
fUNlTiED ' STATES ‘ PATENT OFFICE
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72,405,474
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Thomas (3..' Van
BALANCING
Degrift, Detroit, Mich, a'SSignOr
to General Motors Corporation, Detroit, Mich“
a corporation of Delaware
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Application November 27, 1942, Serial No. 467,113
-11 Claims. (cilia-.66)
.27
1 l
This invention relates to ‘balancing means and
more‘speci?cally'to means for dynamically bal
ancing, a rotating part at substantially the speed
at which it will normally operate in service;
ter of the‘top cross membersB'and Ill are‘sup
ported'a pair of 'spaced'?e'xible leaf spring mem
bers ‘l2 ‘and I6 ‘on'e'ach side. These resilient
leaf . spring ’ members » extend "down I to. approxi
Dynamic forces applied to a rotating body occa
sion ‘various vibrations which cannot be antici
' mately the ‘center offithe'framefformed IbyIthe
side members and-support upon their lower-‘ends
an open bearing member'IB, the upper surface
ofv which is‘grooved to form a substantiallysemi
circular portion ‘20,1'into which‘ may be insertedv
the ends of ‘a ‘cradle assemblyiincluding the'p'ort
pated by statically balancing the device and it is
therefore necessary in many instances and espe
ciallywhere the rotative speedis high to care
fullybalance bodies dynamically so that they
maycoperatesatisfactorily and ‘not be subject
to vibrations-set up'by dynamic forces therein.
tobe-tested. ’ This assemblyicomprises a pair of
It’ is therefore an’ objectof my invention to .
provide a- means for dynamically balancing a
rotating part.
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side plates formed of aiseries of radiating arms‘
22 which extendoutwardly from a center hollow’
hub 24 which is cylindrical and has upon its
15 outerf'end -'a smaller cylindrical member 26. 'The
.It is a further object of; my invention to pro
vide an assembly of driving means and a part to
ends of‘ the radiating arms ‘22 are connected'to
be dynamically balanced, which maybe easily
ber byspacing connecting means‘ 28. 'This 'as
inserted into supporting means.
sembly' therefore'forms a'hollowdrum-like frame
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thelopposite frame arms on the other side mem
It is a still ‘further object of my invention 20 into which maybe inserted ‘the device to be
to provide a‘resiliently mounted supporting "as
sembly into which a previously assembled driv
in the transverse members'28 to lift one frame
ing and driven means may be easily inserted.
member from the other.
It is a still further object of my invention to
tested simply ‘by removing'the securingfme'ans
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“Fixedly secured to one‘ of the central "cylin-e
provide a balancing machine for rotative parts
drical members 24 is a motor ?eld stator winding
which is simple and rugged in construction.
With these and other objects in view which
will become apparent as the speci?cation pro
3!] capableof creating a rotating ?eldiwhen‘ener
gized. The cylindrical ‘members 26 each carry
adjacent their ends where they enlarge into' the
portions 24 a’bearin'g member 32 which is adapted
ceeds, the embodiments ‘of my invention will‘ be
best understood by reference to the following 30 to support the shaft '34 ‘of a rotor 36 to be tested
speci?cation and claims and the illustrations ‘in
which has laminations vin the manner of conven-'
the accompanying drawings, in which: _'
tional squirrel cage induction rotors. The end
Figure 1 is a vertical section taken through a‘
of the rotor ‘shaft projects into the hollow space
machine embodying my invention;
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Figure 2 isan enlarged detail sectional view
taken on line 2-2 of Figure 1;
Figure 3 is an end view of the angular index
ing device;
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Figure 4 is an end view of ‘the mechanism taken
on line 4-4 of Figure 1, parts being broken away
and shown in section;
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Figure 5 is a schematic wiring diagram of the
indicating means associated with the vbalancing
machine;
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Figure 6 is‘a schematic circuit diagram show
ing the 'pick-p-up unit connected to the indicating
left in'the cylindrical'portion 26 in each instance
35 and on one end ‘has‘forced thereover a‘press-e
?tted coupling "38 'which'isj supported upon a
transverse shaft 4!],‘th'e latter being trunnioned
in bearing '42 carried by upright'M on the base‘
2. On ‘the opposite side of the bearing“ a disc
40 46' is ‘applied to the shaft and is" adapted to
rotate therewith. This disc ‘is formed of insu
lating material'and at- one po-rtion'adjacent ‘its
periphery-carries an axial pin 1580f conductive
material. Also ‘mounted ‘on the ‘upright 44 is
'-an electromagnetic coil 50 having a U-shaped
core‘terminating in two projecting pins‘52 and
means; and
54 which extend toward each other leaving an
air gap therebetween' in which the disc 46 ‘and
axial pin '48‘ rotate. Thus once each revolution’ of
50 the shaft " the pin 48 ‘will lie normally between
Referring vnow -more specifically to' Figure 1,
the members 52 and 54 and decrease ‘the reluc
there is “shownltherein a base 2 upon which is
tance of the'magnetic circuit to cause the coil
mounted a pairiofvertical frame ‘members 4 and
as to ‘provide-an impulseand in this manner
6 :which; are connected.‘ together : by horizontal
give an angular impuise or index-for the rotating '
Figure’T-is-"a detailed sectional view showing a
different (type of vibration condenser pick-up
means.
top
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,Ymembersj and-rill; Adjacent the ‘Gen-a
member
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2,405,474
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.There is provided a small pin 56 which is an
chored in the lower portion ofthe cradle mem
ber 18 and which projects through an opening
58 in the cylindrical portion 28 of the frame
to prevent the frame per se from turning. Thus
on an application of power to the stator wind
ing 38' through the terminals 68 the rotor 35
may be ‘caused to rbtate about‘its axis ,on its ,
shaft SQ-in'bearin'gs "32'which rotation‘will also
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two frequencies are the same and by knowing
the frequency of the oscillator the rotative speed
of the test part will be known. An adjustable
capacitor 88 is provided to vary the frequency
of the known oscillator.
In order to ascertain the amplitude of the
vibrations which are picked up by the condenser
pick-upmeans ‘formed of the1 two plates 12-456,
the latter ‘are connected'by lines 98' andv 92 with
cause the shaft 49 and index disc 46 to rotate, 10 the vertical displacement circuit of the oscillo
the remaining portion of the frame being held > graph and therefore as the capacity varies be
‘ tween these plates the potential across the ver
stationary by pins 55. As the rotor rotates at
tical oscillograph plates will vary and cause ver
its given speed, if there are forces of unbalance
tical displacement of the cathode beam to give
which are brought into play by such rotation, the
members I8 supported on the resilient‘stri'ps i2; 15 1a direct reading of‘ the amplitude of these hori
and IE will be caused to move in a horizontal ‘ " 7zontal vibrations. —' I' have thus provided a means
plane by such force.
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In order to pick up this vibration, I have pro
forimpressing a potential indication of the am
plitude of said vibrations and also an angular in
dexing means to determine the angular position
vided a bracket 62 which extends from the'side
frame members 4 or 6 and which supports upon 20 of the maximum vibration forces since the num
ber~of;;angular degrees from the starting poin
its outerend a hollowcylindrical casing 64 with:
can;;be?guredfromlthe oscillograph. -; _» _- _
in onezend'of which :is insulatedly; mounted a
-~-Referring to ‘Figure 7, there is therein shown
disc‘S? connected by a suitable line 68 with indie
a modi?ed pick-up form inwhich a stud-94 is
eating apparatus to be described. , The oppositev
end of the cylindrical casing 64 Jmovably supports 25. threaded intoi'one side‘ of the cradle member
!8 and carries an insulating washer 96 and a
a rod'lll upon one end of which is secured a
smaller insulating washer 98. Mounted between
second spaced-disc 12 which is brought into jux
these two insulating parts and having an-open
taposition with the ?rst disc 66. This rod also
ing Hi0 therethrough of larger diameter than
carries a small disc 14 between which and a por
tion of the casing there‘ is mounted a concentric 30 the'stud is a resilient lever or bar I02 which is
?rmly clamped to the stud but insulated there‘
spring 16 to spring bias the rod outwardly. The
from. The projectingend of the .bar carries a
end of- this rod is brought into ‘juxtaposition and
weight Hi4 which projects to within a short dis
bears against a face of the cradle member 18
tance of a member I06 connected to the cradle
and is therefore moved back and forth by any
58. A conductor I08 is connected tov one end of
horizontal vibration thereof. . This movement
the member V102 and a second conductor H0 is
thus alters the distance between the two discs
connecteddirectly to the stud and therefore to
12 and 66 which form a condenser and therefore
the remainder of the apparatus; Upon vibration
varies the capacity of-the same to give‘ indica
the weight 104 will therefore move back and
tions. One of these 'units is provided adjacent
forth relative to the member I06 and the capacity
each bearing member. In order to maintain the
thereby formed will be varied in much the same
hearing or :cradle member against‘the end of the
manner. as the capacity pick-up formerly de
rod ‘H! a spring 18 is provided which has one
scribed. However, this construction is consider
end secured to the cradle member and the oppo
ably simpler and in some instances it maybe
site end adjustably secured to the frame through
desirable to use this instead of the former de
thumbscrew
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.4 In operating the balancing machine therefore
the two frame members ‘are taken apart, the
stator winding 39 remaining secured to one and
the ‘rotor to be tested is inserted with one end of
vice. . Its function in the system would however
be
the same.
I claim:
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1., In a machine for balancing rotating parts,
its shaft in bearing 32 on the frame member car 50 a base, a pair of spaced open bearing members
resiliently mounted on. the base,’ a. driving stator
rying the stator. The other frame member is‘
?eld assembly for. supporting a driven rotor to
then applied, the other end of the rotor shaft
extending through the second-bearing 32 and the
spacing means 28 is secured at the'ends of 'arms
be .tested adapted to be slung in the bearing
members, and pickup means mounted on the base
22. This assembly is then laid in the'open bear
ings [8, the pins 56 preventing the assembly from,
turning. The coupling 38 is pressed onto the end
of the rotor shaft to drive the angular indexing
adjacent each bearing member’, having a‘ por
tion extending into contact therewith to pick up
the Vibration of the bearing member due to ‘the
means and the-condenser pick-up means are then
- 2.;In a machine-for‘balancing'a~rotating part,
of course remain stationary indicating that the
tially semi-cylindrical groove in the bearing mem
rotation of the rotor.
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adjusted so that the spring-biased rods ‘I0 con 60 a base, a plurality of spaced uprights mounted'on
the base, a pair of resilient strips supported from
tact the cradle members I8. The machine is
the uprights on each side, an open bearing mem
then in readinessfor testing the rotor.
ber secured to the lower end of each pair of
The ‘disc 45 and its associated electromagnet 59
strips, a cradle mounted in the open- bearing
provides the angular index, the latter being con
members, astator driving ?eld supported by the
nected through line 82 with an oscillograph 84
cradle, said rotating part being rotatably sup
and is so connected as to trigger the horizontal
ported in juxtaposition to and driven by the
sweep circuit of the same so that at the instant
stator on the cradle and vibration pick-up means
the pins 48 passes between the pins 52 and 54
mounted on the base and contacting the bear
the sweep circuit is'caused to start, thus giving
this point as the beginning of the wave on the 70 ing members.
3. In a machine for balancing rotating part
oscillograph. In order to ascertain the speed, an
a'base, a plurality of spaced upright supports,
oscillator of known frequency 86 may be con
a pair of spaced bearing members resiliently
nected to the oscillograph and when the two fre
supported from said upright supports, a substan
quencies coincide the wave appearing thereon will
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2,405,474
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bers, cradle means to enclose and rotatably sup
port a part to be balanced comprising a pair
of side members having radial arms detachably
tested, means for securing the ends of the arms
together in de?nite spaced relation, a driving
stator ?eld winding rigidly mounted within the
enclosure formed by the spaced cradle members
in juxtaposition to the rotor to rotate the same,
said hollow cylindrical cradle portions being non
rotatably mounted in the resiliently mounted
connected together at their outer ends and cen
tral hollow shafts, which latter shafts are trun
nioned in the spaced bearing members, and means
for locking the shafts against rotation in the
bearing members.
bearing members, and angular indexing means
4. In a machine for balancing rotating parts,
secured to and driven by the rotor shaft.
a base, a plurality of spaced upright supports, 10
8. In a machine for balancing rotating parts,
a pair of spaced bearing members resiliently sup
resiliently mounted spaced aligned bearing mem
ported from said upright supports, a substan
bers, spaced cradle members comprising hollow
tially semi-cylindrical groove in the bearing mem
cylindrical central portions and radially extend
bers, cradle means comprising a pair of spaced
ing arms for rotatably supporting a rotor to be
separable side members having radial arms con 15 tested, means for securing the ends of the arms
nected together at their outer ends and central
together in de?nite spaced relation, a driving
hollow shafts for rotatably Supporting a rotat
stator ?eld winding rigidly mounted within the
able part to be balanced having shafts, said cradle
enclosure formed by the spaced cradle members
shafts being trunnioned in the spaced bearing
in juxtaposition to the rotor to rotate the same,
members, means for locking the cradle shafts 20 said hollow cylindrical cradle portions being non
against rotation in the bearing members, a driv
rotatably mounted in the resiliently mounted
ing stator coil ?xedly mounted within the cradle
bearing members, a transfer shaft connected to
in juxtaposition to the rotatable part, a trans
the rotor shaft and means for generating an
fer shaft coupled to the rotor shaft, and angular . electric pulse once per revolution connected to
indexing means driven by the transfer shaft.
25 and driven by said shaft.
5. In a machine for balancing rotating parts,
9. In a balancing machine for balancing ro
a base, a plurality of spaced upright supports,
tating parts, a supporting frame, a plurality of
a pair of spaced bearing members resiliently
spaced aligned open bearing members resiliently
supported from said upright supports, a substan
slung from the frame, a driving stator ?eld as
tially semi-cylindrical groove in the bearing
sembly for mounting a driven rotor to be bal
members, cradle means comprising a pair of
anced supported in the bearing members, and
spaced separable side members having radial
means whose electrical capacity will be changed
arms connected together at their outer ends and
by relative movement between parts thereof
central hollow shafts for rotatably supporting a
mounted adjacenteach bearing member and sub
rotatable part to be balanced having shafts, said 35 ject to the vibrations thereof caused by the rota
cradle shafts being trunnioned in the spaced
tion of the rotor.
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bearing members, means for locking the cradle
10. In a balancing machine for balancing ro
shafts against rotation in the bearing members,
tating parts, a supporting frame, a plurality of
a driving stator coil ?xedly mounted within the
spaced aligned open bearing members resiliently
cradle in juxtaposition to the rotatable part, a 40 slung from the‘frame, a driving stator ?eld as
transfer shaft coupled to the rotor shaft, angular
sembly for mounting a driven rotor to be bal
indexing means driven by the transfer shaft, said . anced supported in the bearing members, a plate
angular indexing means comprising a disc ?xed
mounted in insulated relation with respect to
to the transfer shaft, a pin carried by the periph
the frame, a second spaced plate mounted in
ery of said disc and magnetic means mounted
contact with the open bearing members whereby
adjacent the disc periphery whose ?eld is altered ‘
a condenser is formed by the two plates and vi
by the passing of the pin to give an angular index
bration of the bearing members due to rotation
point.
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6. In a machine for balancing rotating parts,
resiliently/mounted spaced aligned bearing mem
bers, spaced cradle members comprising hollow
cylindrical central portions and radially extend
ing arms for rotatably supporting a rotor to be
tested, means for securing the ends of the arms
together in de?nite spaced relation, a driving sta
tor ?eld winding rigidly mounted within the en
closure formed by the spaced cradle members in
juxtaposition to the rotor to rotate the same, said
hollow cylindrical cradle portions being non-ro
tatably mounted in the resiliently mounted bear
ing members.
7. In a machine for balancing rotating parts,
resiliently mounted spaced aligned bearing mem
bers, spaced cradle members comprising hollow
cylindrical central portions and radially extend
ing arms for rotatably supporting a rotor to be
of the rotor will cause capacity variation and
provide an indication of such vibration.
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11. In a balancing machine for balancing r0
tating parts, a supporting frame, a plurality of
spaced aligned open bearing members resiliently
slung from the frame, a driving stator ?eld as
sembly for mounting a driven rotor to be bal
55 anced supported in the bearing members, an arm
projecting from each open bearing member, a
stud threaded into the bearing members, a ?ex
ible arm insulatably mounted on each stud, a
weight on each ?exible arm projecting in juxta
60 position to the ?rst named arms and forming an
electrical condenser therewith whereby vibration, .
of each bearing member will cause relative move- '
ment between the arms and therefore capacity
change to indicate vibration caused by rotation
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of the rotor.
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THOMAS C. VAN DEGRIF'I‘.
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