Bearing roller gauge

The diametral variations around the circumference of a bearing roller are measured by mechanical-to-electrical transducers which convert the diametral variations into electrical signals which are functions of the variations. The frequencies of the electric signals are converted into electric spikes which are proportional to the actual effect on roller noise of the frequency represented by each spike. The spikes are electrically added and a print is made of a value which is proportional to the expected noise the roller will produce when used in a roller bearing.

This invention relates to roller bearings. More particularly, this 
invention is a method and apparatus for measuring the diametral variations 
around the circumference of a roller. 
One of the steps used to manufacture rollers for roller bearings is to 
grind the rollers in machines known as centerless grinders. This grinding 
operation produces small periodic undulations that appear on the surface 
of the rollers. These undulations are commonly called "grinder chatter" 
and appear between 12 and 60 times around the circumference of the roller. 
The most common form of chatter occurs toward the middle of this range, 
between 20 and 40 undulations. 
Conventional roller roundness measuring equipment is not constructed to 
detect undulations due to grind chatter. The conventional equipment does a 
reasonable job of measuring lobing, that is, less than 12 undulations 
around the circumference, but in most cases lobing is less a noise 
producer than the chatter undulations. 
The U.S. Pat. No. 3,745,815 granted to Bentone et al, July 17, 1973 and 
entitled "DEVICE FOR EVALUATING THE VIBRATIONS OF A REVOLVING MEMBER", 
discloses a device that mounts a ball bearing on a rotating spindle in 
order to evaluate its vibrations. Bentone, however, does not disclose or 
suggest an apparatus or method to measure variations in the diameter of a 
roller. The U.S. Pat. No. 3,795,055 granted to Zucco, Mar. 5, 1974 and 
entitled "APATUS FOR DIMENSIONAL TESTING OF NOMINALLY CYLINDRICAL 
WORKPIECES" discloses an apparatus for measuring the diameter of a 
cylindrical workpiece utilizing two opposing transducers. The device of 
Zucco, however, does not rotate the tested object on a spindle but rather 
only turns it 180.degree. about the axis of a "V" support. 
The roller gauge of this invention is constructed to not only detect and 
measure chatter, but also to make an accurate prediction of how much noise 
energy the roller is likely to generate in operation. 
Briefly described, the roller gauge comprises a means for rotating the 
roller. Mechanical-to-electrical transducer means convert the diametral 
variations of the roller into electrical signals which are a function of 
the diametral variations. An electric signal conversion system converts 
the electrical signals from the transducer into a meaningful indication of 
the diametral variation of the roller 
Our new method of indicating the diametral variations of rollers comprises 
the steps of rotating the rollers, electromechanically converting the 
diametral variations around the circumference of the roller into 
electrical signals which are a function of the diametral variations, and 
converting the electrical signals into a meaningful indication of the 
diametral variations of the roller.

In the various figures, like parts are referred to by like numbers. 
Referring to the drawings and more particularly to FIG. 1 and FIG. 2, 
conventional roundness equipment measures the radial deviation around the 
circumference of the roller. While this may provide some useful 
information, we have found that measuring the diametral variation is a 
more accurate way to look at the surface of a roller for noise producing 
defects. The reason for this is that when the roller bearing is operated 
it only "sees" from a diametral standpoint. The similarity between how the 
bearing and the diametral gauge each measure the roller diameter is 
illustrated in FIG. 1 and FIG. 2. In FIG. 1, the roller 10 rolls within 
the annulus between a rotatable shaft 12 and an outer race 14. In FIG. 2, 
the gauge includes an upper transducer 16 and a lower transducer 18 which 
measures the diameter of the roller 10. Thus, FIG. 1 and FIG. 2 illustrate 
the similarity between how the bearing and the diametral gauge each 
measure the roller diameter. 
As shown in FIG. 3 and FIG. 4, the physical measurement of the roller 
diameter in the gauge results in an electrical signal which may be fed to, 
for example, a lineal variable distance transducer. The 
mechanical-to-electrical transducers 16 and 18 convert the physical 
measurement into electrical signals which are a function of the diametral 
variation. FIG. 3 and FIG. 4 are examples of what the wave forms 20 and 22 
would look like for rollers that have 5 lobes and 30 chatter undulations, 
respectively. 
The amplitude of the wave formed is proportional to the roller diameter 
variations detected by the transducers. A perfectly round roller would 
have no diametral variations and, therefore, the wave form would show a 
straight line at the zero amplitude level. In actual practice, even very 
good quality rollers have some diametral variation which will be detected 
by the gauge. 
The wave form information shown in FIG. 3 and FIG. 4 is useful for giving a 
visual indication of the diameter variation. In simple cases, we can also 
use it to count the number of undulations and to estimate their average 
amplitude. To improve accuracy, however, we take the wave form signals 
shown in FIG. 3 and FIG. 4 and perform a frequency analysis on them. This 
is really the only way that complex real-world roller shapes can be 
quickly reduced to their component frequencies. The frequency analysis of 
the roller examples shown in FIG. 3 and FIG. 4 are shown in FIG. 5 and 
FIG. 6, respectively. 
Each of the components, or "spikes", 24 and 26 give a simplified 
interpretation of the wave form from which it was derived. Using a single 
vertical line, these spikes can convey both the frequency and the average 
amplitude for their respective wave form. Because of their complexity, 
real-world roller signals may have many more frequency spikes. However, 
the principle of frequency analysis is always the same as these simple 
cases. 
At this point, we now have a simplified frequency analysis of a more 
complex wave form, but we still have to perform some additional processing 
of the information. The reason for this is due to the fact that the 
frequency of the wave form has a great deal to do with how noisy the 
roller will be in the bearing. All wave form frequencies are not created 
equal, where roller noise is concerned. The lower frequencies in the 12 to 
60 undulations range do not contribute a great deal toward roller noise. 
The frequencies become more important as we move to the higher 
frequencies. In the upper half of the frequency range (30 to 60 
undulations), any frequency spike at all seems to cause some roller noise. 
In order to resolve this frequency inequality, we electronically convert 
the frequency plot so that the height of the spike 24 shown in FIG. 7 is 
reduced to the spike 28 of FIG. 7 while the height of the spike 26 in FIG. 
8 is enlarged to the spike 30 in FIG. 8. In the resulting frequency plot, 
the spikes are always shown proportional to their actual effect on roller 
noise. The two spikes are now shown in their proper relative height as 
they effect the roller noise levels. Note that spike 30 now appears much 
higher than the spike 28. This is as it should be to show their relative 
contribution to noise. 
The final step in the roller chatter measurement is to take the converted 
frequency plot and reduce it down to a single meaningful number. The 
spikes of all the frequencies are electronically added and a total RMS 
value for that particular roller is printed. This appears in the upper 
right-hand corner of the converted frequency plots of FIG. 7 and FIG. 8. 
This value can then be compared to some specified level for the roller 
being evaluated. It can be seen that for our two hypothetical rollers, the 
one that has the five lobes (but no chatter) came in with a very low 
reading of 0.005 RMS, while the roller with chatter (but no lobing) was an 
order of magnitude higher at 0.050 RMS. In looking at real-world rollers, 
it is seldom a case of having only chatter or only lobing, since usually 
both are present to some degree. The more complex the roller geometry, the 
more useful this gauge becomes in sorting out what is important with 
regard to noise. 
Referring to FIG. 9, the roller 10 is mounted on the spindle 32 which is 
rotatable within housing 34. The diametral variations in the roller around 
its circumference are converted into wave forms such as shown in FIG. 3 
and FIG. 4 but having many more frequencies than shown in FIG. 3 and FIG. 
4 and fed to the SIGNAL DETECTOR AND AMPLIFIER 36. From the SIGNAL 
DETECTOR AND AMPLIFIER 36, the wave form is fed to the WAVE FORM 
MEASUREMENT CIRCUIT 38 and displayed on a display 40. The signals are then 
fed to the FREQUENCY ANALYZER 42 where the complex frequencies from the 
WAVE FORM MEASUREMENT CIRCUIT 38 are converted into spikes similar to the 
spikes shown in FIG. 5 and FIG. 6 and displayed on the display 44. The 
spikes from the FREQUENCY ANALYZER 42 are then fed to the WEIGHTING 
CIRCUIT 46 where the spikes from the FREQUENCY ANALYZER 42 are converted 
into a plurality of spikes like the spikes 28 and 30 of FIG. 7 and FIG. 8, 
respectively, which are proportional to the actual effect on roller noise 
of the frequency represented by the spike. These spikes are displayed in 
display 48. The spikes from the WEIGHTING CIRCUIT 46 are then fed to the 
ADDER CIRCUIT 50 where all the spikes are electrically summed and a print 
of the RMS value is displayed on display 52.