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Патент USA US3023613

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March 5, 1962
K. M. GORDON ETAL
3,023,604
BEARING VIBRATION AND NOISE TESTER
Filed Oct. 2, 1959
2 Sheets-Sheet 1
FIG. 1
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INVENTOR
KEITH M. GOR
N
DAVID E. C LARK
BY THEODORE BARNARD
ATTORN
S
March 6, 1962
K. M. GORDON ETAL
3,023,604
BEARING VIBRATION AND NOISE TESTER
Filed Oct. 2, 1959
2 Sheets~Sheet 2
Loudspeakr Oscilope Vibraton Metr
35
32
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Audio
Amplifer
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FIG.2
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Compresd Suply
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Alr
Timer
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Amplifer
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R.P M. Met r
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Pre-Amp.
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Pulse
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Counter
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Bearing Testr Vibraton PCiocklup E524 R.PM PCiocklup
A
INVENTORS
KEITH M. GOR DON
BY DAVID E CLARK
.
THEODORE 'P.
ARNARD
Van/“z W WM; M
f %@
ATTORN S
United States Patent 0
1
C6
3,023,604
Patented Mar. 6, 1962
2
vibrations is provided by way of a loudspeaker which
3,023,604
BEARING VIBRATION AND NOISE TESTER
Keith M. Gordon, Westmoreland, and David E. Clark
and Theodore P. Barnard, Keene, N.H., assignors to
Miniature Precision Bearings, Inc., Keene, N.H., a cor
poration of New Hampshire
Filed Oct. 2, H59, Ser. No. 843,957
reproduces the ampli?ed electrical vibration signals oc
curring in the audible frequency range. In addition an
oscillosope is provided as a visual aid for evaluating the
displayed electrical vibration signals.
For a more completeunderstanding of the invention
reference should be had to the accompanying drawings
8 Claims. (Cl. 73-9)
in which:
FIG. 1 is a sectional view of the bearing vibration and
The present invention relates to test instruments for 1O noise tester showing the general arrangement of parts;
measuring the overall dynamic operating quality of a ball
FIG. 2 is a block diagram of the electrical circuits
bearing assembly, and more particularly to an instrument
employed in a preferred embodiment of the bearing vibra
which is adapted to test such a ball-bearing assembly by
tion and noise tester.
rotating the outer race and measuring the axial vibrations
Referring to the drawings there is shown in FIG. 1
produced on the inner race.
15 a bearing tester 10 comprising a cylindrical housing 11
In many phases of industry there exists a great un?lled
mounted on plate 12, which is in turn supported by base
demand for a simple, inexpensive test instrument which is
plate 13 with vibration shock-mounts 14». A ball-bearing
capable of providing a speedy qualitative evaluation of
assembly comprising inner race 15, outer race 16 and ball
precision ball-bearing performance. The need for such a
elements 17 is shown mounted on ?xed vertical spindle 18
test instrument is particularly keen in applications where 20 which is in turn supported by the housing by flexible
the ultimate in smooth performance and extreme reliability
diaphragms 19. A rotor drum 20 made of non-magnetic
are paramount requirements. The instrumentrprovided by
material such as aluminum is mounted on the outer race
this invention has extremely high sensitivity to damaged
of the bearing to be tested. This rotor element provides
or contaminated bearings and is adapted to ful?ll the
the necessary desired axial loading on the bearing under
aforementioned needs by measuring the minute vibrations 25 test and at the same time provides the mechanical cou
set up along the axial direction on an axially loaded driven
pling required to drive the outer race of the bearing. Ro
bearing which are produced by rough surfaces on the
tational drive for the rotor is effected by a pair of air
ball elements, rough raceways, foreign particles, brinell
jets 21, 21’ which are directed at an angle (approx. 15°)
marks and the like.
towards the grooves 22 embossed on the outer periphery
In general the instrument of this invention is adapted 30 of the rotor. Compressed air is supplied to the driving
, to measure the aforementioned bearing defects and others
jets via duct 23 from a valve-controlled compressed air
by driving the outer race of a test bearing which has been
supply the operation of which will be described more
loaded in the axial direction and measuring the axial
‘fully hereinafter. One of the chief advantages of the air
vibrations produced on the inner race. In a preferred
driven rotor provided by this invention lies in the fact
embodiment of the invention a velocity sensitive electro 35 that rotation is effected without introducing undesired ex
mechanical transducer is employed to sense the axial
ternal vibration from the rotor drive system, into the
vibrations. The inner race of the bearing is mounted on
measuring instrument.
'
a vertical spindle which is suspended in space by a pair
A velocity sensitive electromechanical transducer com
of ?exible diaphragms mounted in a suitable cylindrical
prising a multiple-turn cylindrical coil 24 mounted on
housing. A non-magnetic rotor drum is mounted on the 40 spindle 18 and a permanent magnet 25 mounted in the
outer race and rotated by a plurality of air jets to a de
base of the housing is provided to measure the axial vibra
sired measuring speed. Thus only the outer race of the
tions produced on the ?xed inner race when the outer
bearing is rotated and the axial vibrations produced on
race is rotated by the air driven rotor load. Vibrations
the ?xed position inner race by hearing defects are sensed
produced on the inner race due to bearing defects cause
by a velocity-sensitive transducer comprising a multiple 45 the entire spindle and coil to vibrate on the ?exible dia
turn coil mounted on the opposite end of the vertical
phragms and thereby cause a voltage to be produced
spindle and adapted to move through a magnetic flux
across the pickup coil 24 when said coil is movedrthrough
?eld. A signal Voltage is produced in the vibration pickup
the magnetic lines of ?ux produced by permanent magnet
coil the amplitude of which is proportional to the velocity
25. The voltage produced by this coil, which isppropor
of the bearing vibration.
50 tional in amplitude to the velocity of the bearing vibra
A plurality of small permanent magnets mounted.
equally spaced around the periphery of the rotor drum
function cooperatively with a separate ?xed position
pickup coil to generate electrical pulses at a frequency
which is proportional to rotor speed. These pulses are 55
counted by an electrical counter circuit which is employed
to automatically turn off the compressed air supply when
the rotor has reached a given desired rotational speed. At
tion, is connected to measuring circuits with conductors
26, 26'. The operation of these circuits will be explained
more fully hereinafter in conjunction with FIG. 2.
The rotational speed of the rotor is measured by pulse
generating apparatus comprising a multiple-turn-pickup
‘coil 27 and eight permanent magnets 28 (two shown)
equally spaced around the periphery of the rotor. A volt
age pulse is produced across the coil output leads 29,5 29’
the same time an automatic timer is turned on to measure
each time one of the permanent magnets rotates past the
the spin down time required for the bearing to coast or 60 pickup coil. The rate of incidence or frequency of these
spin down from the aforementioned maximum speed to
generated pulses is measured to determine the rotational
some predetermined minimum speed. A qualitative meas
speed of the rotor and hence the speed of vthe outer
ure of bearing running torque is thereby expeditiously’ef
bearing race.
fected.
Referring to FIG. 2 there is shown therein a simpli?ed
The electrical signals produced by the velocity sensi_ 65 electrical block diagram of the circuits provided in ac
tive electromechanical transducer are ampli?ed and meas
cordance with the teachings of this invention. The elec
ured by a peak-reading voltmeter which may be cali
trical vibration signals produced across pickup coil 24
brated to read maximum motion or velocity.
Thus a
qualitative measure of the magnitude of the vibration
are connected via conductor 26 to pre-ampli?er 30.
The output signal of pre-ampli?er 30 is connected to
producing defects of the bearing is effected by the test in 70 audio ampli?er 31 which drives loudspeaker 32 and also
to a “scope” and meter ampli?er 33 which supplies oscillo
Further means for evaluating the nature of the bearing
scope 34 with an ampli?ed vibration signal for visual dis
strument.
'
.
.
8,023,604
3
4
ments. In certain instances on the other hand it will be
advantageous to calibrate the meter in units of velocity,
e.g., microns-per-second. One method which has been
found to be satisfactory for effecting such a calibration
play purposes. A second signal output is supplied by‘the
“scope” and meter ampli?er to vibration meter 35 which
is adapted to measure the maximum peak-to-peak vibra
tion signal produced by the test bearing during a test
cycle interval. The frequency response of the ‘above men
tioned ampli?ers is substantially ?at from 200 cycles to
has involved driving the vertical spindle and pickup coil
with an external electromagnetic system which is ener
gized by an alternating current of a known frequency and
measured amplitude. The mass of the entire system in
10 kilocycles. Operating tests have established that most
of the axial bearing vibrations fall in a frequency range
between 500 and 1000 cycles per‘ second, with the exact
‘cluding the spindle, measuring coil and driving coil is
range being determined primarily by the axial yield rate of 10 ‘measured and the force F produced by the A.-C. driving
current may then be computed by proportion after the
the bearing and the mass of the spindle and vibration
amount of coil current required to suspend the coil (a
known mass) in the vicinity of the magnet has been
measured. The velocity V is computed from the well
ing, as a practical matter the speed is advantageously
selected to fall in a range between 600 and 1800 r.p.m. 15 known equations V=AT where T :time and A=accel
eration (Force/Mass).
At higher speeds any dynamic unbalance present in the
While a preferred embodiment of the invention has been
rotor will introduce spurious vibration components in the
shown
and described herein, various modi?cations within
bearing measurements.
the
scope
of the appended claims will be apparent to those
The rotational speed of the rotor drum is measured by
an electronic tachometer comprising pickup coil 27, pulse 20 skilled in the art.
We claim:
counter 36 and an r.p.m. meter 37. Eight permanent
1. Apparatus for testing a ball-bearing assembly compris
magnets located around the periphery of the rotor drum
ing
in combination, a housing, means for supporting said
are provided to generate voltage pulses in the pickup
bearing assembly comprising a spindle which is adapted
coil 27 when the rotor is rotated by the air jets. The
frequency of the periodic pulses induced in the coil is 25 to mate with the inner race member thereof, means for
vertically supporting said spindle in said housing, said
proportional to the rotational speed of the rotor. Pulse
means including a pair of ?exible diaphragms, means for
counter 35 produces an output voltage which is propor
axially loading said bearing assembly comprising a rd
tional to the frequency of the incoming ‘pulses-and this
tor drum which is adapted to mate with the outer race
voltage is measured by.r.p.m. meter 37 which may be
coil. While the frequency range of these vibrations is
substantially independent of rotational speed of the bear
calibrated with the aid of a tachometer to read directly in 30 member thereof, means for rotating said rotor drum
revolutions per minute.
.
In addition to the normal moving hand 38, meter 37
also has a high limit hand 39 and a low limit hand 40.
comprising a plurality of spaced jets which are adapted
to be energized by compressed gas, an electro-mechanical
transducer associated with said spindle for producing
an output signal voltage which is proportional in ampli
These hands carry electrical switch contacts which func
tion cooperatively with switch contacts on the moving 35 tude to the velocity of axial vibrations produced there
on, said transducer including a low mass pickup-coil
hand to provide the desired speed control switching cir
mounted on said spindle with means mounted on said
cuits. Both limit hands are adjustable by individual knobs
housing for producing a ?xed magnetic ?eld surround
located on the front face of the meter.
ing said coil, and indicator means for measuring said
In a typical test cycle the upper limit hand would be set
signal voltage.
at 800 r.p.m. for example, and the lower limit hand at
2. Apparatus for testing a ball-bearing assembly in
say 400 r.p.m. After the solenoid controlled ‘air valve 42
accordance with claim 1 in which said indicator means
is opened by pushing a start button, the jet driven rotor
comprises anoscilloscope, a loudspeaker and a voltmeter.
increases in rotational speed until the indicator needle
3. Apparatus for testing a ball-bearing assembly com
contacts the upper limit hand at which time the above
mentioned switch contacts function to turn on the auto 45 .prising in combination, a housing means for supporting
said bearing assembly comprising a spindle which is adapt
matic timer 41, turn off the solenoid operated air valve
ed to mate with the inner race member thereof, means
42 and energize the pro-amp 30. When the pre-amp is
for vertically supporting said spindle in said housing,
energized by switching the B+ supply on (or closing a
said means including a pair of spaced ?exible diaphragms
normally open switch in the signal circuit), the loud
speaker and oscilloscope are supplied with the ampli?ed 50 ?xedly secured to said housing around the peripheral
vibration signals and the vibration meter measures the
maximum amplitude of the vibration signals. After the air
supply has been turned ed, the rotor loses speed and the
rpm. indicator hand drops back and touches the lower
limit hand switch-contact thereby turning off the timer.
Thus the instrument of this invention provides an ac
curate, simple, convenient and rapid means for testing the
general quality of precision ball-bearings by detecting the
edges thereof and arranged to permit substantially only
axial displacement of the said spindle, means for axially
loading said bearing assembly comprising a rotor drum
which is adapted to mate with the outer race member
thereof, means for rotating said rotor drum comprising
a plurality of spaced jets which are adapted to be ener
gized by compressed gas, an electro-mechanical trans
ducer associated with said spindle for producing an out
axial vibrations of a loaded bearing driven at a con
put signal voltage which is proportional in amplitude
ured by a peak reading meter for qualitative evaluation.
producing a ?xed magnetic ?eld surrounding said coil,
and indicator means for measuring said signal voltage.
trolled rotational speed. The ampli?ed vibrations are 60 ‘to the velocity‘ of axial vibrations produced thereon, said
transducer including a low mass pickup-coil mounted on
displayed on an oscilloscope for visual evaluation, repro
said. spindle with means mounted on said housing for
duced on a loudspeaker for aural evaluation, and meas
At the same time the instrument automatically measures
4. Apparatus for testing a ball-bearing assembly com
the time required for the bearing to spin down from a 65
prising in combination, a housing, means for supporting
selected maximum speed to a selected minimum speed
said bearing assembly comprising a spindle which is
provding thereby a qualitative measure of bearing friction
adapted to mate with the inner race member thereof,
or running torque. ‘Clearly bearings having low friction
means for vertically supporting said spindle in said hous
between the races require the longest time interval for spin
down while those bearings having high friction (rough 70 ing, said means including a pair of ?exible diaphragms,
means for axially loading said bearing assembly com
races, rough ball elements, dirt, etc.) require a much
prising a rotor drum which is adapted to mate with the
shorter time interval for spin down.
outer race member thereof, means for rotating said ro
The vibration meter shown at 35 in FIG. 2 may be
‘tor drum comprising a plurality of spaced jets which
‘calibrated in arbitrary units where the instrument is em
ployed to make comparative bearing vibration measure 75 are adapted to be energized ‘by compressed gas, elec
8,023,604
trically operable valve means for controlling the supply of
compressed gas to said jets, tachometer means for meas
uring the rotational velocity of said rotor drum, an elec
trical time-interval clock for measuring the spin-down
time of said bearing, ?rst switch means operatively as
sociated with said tachometer and adapted to be actuat
ed by said tachometer at a selectable maximum rota
tional speed to simultaneously energize said clock and
6
race member thereof, means for rotating said rotor drum
comprising a plurality of spaced jets which are adapted
to be energized by compressed gas, electrically operable
valve means for control-ling the supply of compressed gas
to said jets, tachometer means for measuring the rota
tional velocity of said rotor drum, an electrical time-in
terval clock for measuring the spin-down time of said
bearing, an electromechanical transducer associated with
close said valve, and second switch means operatively
said spindle for detecting the axial vibrations produced
associated with said tachometer and adapted to be actuat 10 thereon, said transducer being adapted to produce an out
ed by said tachometer to stop said clock at a selectable
put signal voltage which is proportional in amplitude to
minimum rotational speed.
5. Apparatus for testing a ball-bearing assembly in
the velocity of the produced vibrations, ?rst indicator
means for measuring said signal voltage comprising an
accordance with claim 4 characterized in that said rotor
oscilloscope, second indicator means for measuring said
drum is fabricated from a non-magnetic material and said 15 signal voltage comprising a voltmeter, and third indica
tachometer comprises in combination a plurality of per
tor means for measuring said signal voltage comprising a
manent magnets imbedded at equally spaced distances
loudspeaker, ?rst switch means operatively associated
around the periphery of said drum, means for detect
with said tachometer and adapted to be operated by said
ing the rotation of said magnets comprising a pickup
tachometer at a selectable maximum rotational speed to
coil which is adapted to produce periodic voltage pulses 20 energize said clock and to close said valve, and second
at a frequency proportional to the rotational velocity of
switch means operatively associated with said tachometer
said drum, an electronic counter for developing an out
and adapted to be actuated by said tachometer to stop
put voltage proportional in amplitude to the frequency
said clock at a selectable minimum rotational speed.
of said pulses, and indicator means for measuring the
8. Apparatus for testing a ball-bearing assembly com
output voltage of said counter.
25 prising in combination, a housing, means for supporting
6. Apparatus for testing a ball-bearing assembly com
said bearing assembly comprising a spindle which is
prising in combination, a housing, means for supporting
adapted to mate with the inner race member thereof,
said bearing assembly comprising a spindle which is
means for vertically supporting said spindle in said hous
adapted to mate with the inner race member thereof,
ing said means including a pair of ?exible diaphragms,
means for vertically supporting said spindle in said hous 30 means for axially loading said bearing assembly com~
ing said means including a pair of ?exible diaphragms,
prising ‘a rotor drum which is adapted to mate with the
means for axially loading said bearing assembly com
outer race member thereof, means for rotating said rotor
prising a rotor drum which is adapted to mate with
drum comprising a plurality of spaced jets which are
the outer race member thereof, means for rotating said
adapted to be energized by compressed gas, electrically
rotor drum comprising a plurality of spaced jets which are 35 operable valve means for controlling the supply of com
pressed gas to said jets, tachometer means for measuring
adapted to be energized by compressed gas, electrically
operable valve means for control-ling the supply of com
the rotational velocity of said rotor drum, an electrical
time-interval clock for measuring the spin-down time of
pressed gas to said jets, tachometer means for meas
said bearing, an electro-mechanical transducer associated
uring the rotational velocity of said rotor drum, an
electrical time-interval clock for measuring the spin 40 with said spindle for detecting the axial vibrations pro
duced thereon, said transducer being adapted to produce
down time of said bearing; an electromechanical trans
an output signal voltage which is proportional in ampli
ducer associated with said spindle for detecting the
tude to the velocity of the produced vibrations, indicator
axial vibrations produced thereon, said transducer being
means for measuring said signal voltage, ?rst switch means
adapted to produce an output signal voltage which
is proportional in amplitude to the velocity of the 45 operatively associated with said tachometer and adapted
to be actuated by said tachometer at a selectable maxi
produced vibrations, indicator means for measuring said
mum rotational speed to simultaneously supply a signal
signal voltage, ?rst switch means operatively associated
to said indicator, to energize said clock and to close said
with said tachometer and adapted to be operated by said
tachometer at a selectable maximum rotational speed to 50 valve, and second switch means operatively associated
with said tachometer and adapted to be actuated by said
energize said clock and to close said valve, and second
tachometer to stop said clock at ‘a selectable minimum
switch means operatively ‘associated with said tachometer
rotational speed.
and adapted ‘to be actuated by said tachometer to stop
said clock at a selectable minimum rotational speed.
References Cited in the ?le of this patent
7. Apparatus for testing a ball-bearing assembly com
UNITED STATES PATENTS
prising in combination, a housing, means for supporting
said bearing assembly comprising a spindle which is
2,468,648
Abbott et a1 ___________ __ Apr. 26, 1949
adapted to mate with the inner race member thereof,
means ‘for vertically supporting said spindle in said hous
ing said means including a pair of ?exible diaphragms, 60
2,787,905
2,793,525
2,937,518
Prestipino et al. _______ __ Apr. 9, 1957
vMims _______________ __ May 28, 1957
Bjong et al ____________ __ May 24, 1960
927,176
Germany _____________ __ May 2, 1955
means for axially loading said bearing assembly compris
ing a rotor drum which is adapted to mate with the outer
FOREIGN PATENTS
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