FIELD
The present disclosure relates to field of bearing diagnosis.
BACKGROUND
Manufacturing imperfections such as improper tolerances in the components, surface roughness and surface waviness, rather than the physical localized damage can be the 5 cause of deteriorated bearing performance. Further, during the manufacturing process, improper handling can induce faults, such as nicks, scratches, cracks and the like, located in one or more of the bearing elements. Such small variations in the dimensions of the critical components of the bearing due to manufacturing inaccuracies can have a significant effect on the trouble-free operation, reliability, and 10 performance of bearings. Hence it is necessary to identify bearings with dimensional inaccuracies right at the manufacturing stage.
The conventional systems developed in the art estimate the bearing health based on identification of localized defects on the outer race, inner race, rolling elements and cage, which are generally not present in freshly manufactured bearings. Further 15 majority of these approaches are limited to use of a narrow bandwidth spectrum and to a single domain, such as the frequency domain. In other words, the vibration signal is represented as a function over a set of frequencies to identify the fault parameter. However, the proper selection of the filter zone based on visual inspection poses to be a major challenge in the application of this method. Moreover a filter designed for 20 one bearing may not always be appropriate for bearings with different dimensions.
Hence, in order to overcome the aforementioned drawbacks, there is need of a bearing diagnosis system for diagnosing freshly manufactured bearings which is reliable and robust.
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OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide a bearing diagnosis system that can diagnose freshly manufactured bearings as well as used/worn out bearings. 5
Another object of the present disclosure is to provide a bearing diagnosis system that is reliable and robust.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure. 10
SUMMARY
The present disclosure envisages a bearing diagnosis system. The system comprises a probe that is configured to abut an outer ring of a bearing, wherein the outer ring of the bearing is held by a holding arrangement, and an inner ring of the bearing is coupled with a motor to facilitate the rotation of the inner ring with respect to the 15 outer ring that is stationary, thereby inducing vibrations within the bearing. A sensor is coupled with an axial short bar that touches the outer race of the bearing and is configured to sense the bearing vibrations using the sensor (accelerometer). A data acquisition system is communicatively coupled with the sensor and is configured to condition and digitize the raw data. A communication interface cooperates with the 20 data acquisition device and transfers raw time domain vibration data to a storage and processing/computing device. The display device connected to the processing/computing device is configured to display the processed bearing vibration data including a fused parameter to collectively indicate the condition of the bearing.
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In an embodiment, the signal processor further configured to transform the vibration signals from time domain into frequency domain using Fast Fourier Transform (FFT) to generate frequency domain vibration signals; filter out the frequency domain vibration signals in batches of pre-determined frequency ranges to generate filtered vibration signals; transform the filtered vibration signals from frequency domain back 5 into the time domain using Inverse Fast Fourier Transform (IFFT) to generate filtered time domain vibration signals; and fuse the filtered time domain vibration signals to generate the fused parameter.
In another embodiment, the pre-determined frequency ranges include ranges of 80 Hz to 250 Hz, 250 Hz to 400 Hz, 400 Hz to 1200 Hz, 1200 Hz to 2000 Hz, 2000 Hz to 10 3500 Hz, and 3500 Hz to 6000 Hz. These frequency bands are identified through scientific study on measurements made on a variety of deep groove ball bearings manufactured.
In another embodiment, the holding arrangement comprises a pneumatic cylinder, and a holding plate connected with a piston rod of the pneumatic cylinder, wherein 15 the holding plate is configured to hold the outer ring of the bearing while applying a pre-determined load, via the pneumatic cylinder, on the bearing. In another embodiment, the sensor is an accelerometer.
In another embodiment, the accelerometer is supported within a support structure that comprises a first support frame configured to support the accelerometer and the short 20 axial bar. A second support frame is connectable to the first support frame to define a hollow space within which the accelerometer is housed. The second support frame is configured to support a pre-loading arrangement that is configured to apply a pre-load on the accelerometer.
In another embodiment, the pre-loading arrangement comprises a bolt, and a spring 25 configured within the hollow space such that a first operative end of the spring is
5
connected to a first operative end of the bolt, and a second operative end of the spring abuts the accelerometer.
In another embodiment, a linear bearing is configured on the first support frame to circumscribe the probe and allow longitudinal movement of the probe therewithin.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING 5
A bearing diagnosis system of the present disclosure will now be described with the help of the accompanying drawing, in which:
Fig. 1A and Fig. 1B illustrate a schematic view of the bearing diagnosis system, in accordance with an embodiment of the present disclosure; and
Fig. 2 illustrates sectional view of a fixture arrangement used in the bearing diagnosis 10 system.
DETAILED DESCRIPTION
The conventional bearing diagnosis systems employ the use of sound or vibration pickup signals to extract the sound/vibration generated in the operation of a bearing. The bearing is held on the end of the rotating shaft of a quiet running motor with a 15 predefined pressure being applied to the bearing. The vibration signal is divided into three frequency bands: low band (50 to 300 Hz), medium band (300 to 1,800 Hz), and high band (1,800 to 10,000 Hz), and their corresponding RMS values are displayed in either LG/VG or dB. The desired frequency is filtered by hardware filters. The system is also coupled with audio output from the sensor through speakers or headphones. 20 The flaw and defect is identified if noise level is above the predetermined limit set by the customer requirement. When the rejected bearings are checked again, the noise level becomes under the limit. This is caused by either poor repeatability of machine due to hardware filters or due to large frequency bands. The present disclosure
6
envisages a bearing diagnosis system that overcomes the aforementioned drawbacks of the conventional methods for diagnosing bearings.
Fig. 1A and Fig. 1B illustrate a schematic view of the bearing diagnosis system 100 (hereinafter referred to as system 100), in accordance with an embodiment of the present disclosure. Fig. 2 illustrates a schematic sectional view of the system 100. 5 Referring to Fig. 1A through Fig. 2, the system 100 comprises a probe 102 that is configured to abut an outer ring of a bearing 101 that is to be diagnosed, wherein the outer ring 101A of the bearing 101 is held by a holding arrangement 104, and an inner ring 101B of the bearing 101 is coupled with a motor 106 to facilitate the rotation of the inner ring 101B with respect to the outer ring 101A that is stationary, 10 thereby inducing vibrations within the bearing 101. A sensor 108 is coupled with the probe 102 and is configured to sense the vibrations which are generated by the bearing 101. In an embodiment, the sensor 108 is an accelerometer that generates the vibration signals in time domain. A signal processor 110 is communicatively coupled with the sensor 108 and is configured to receive and process the vibration signals to 15 obtain digitized vibration signals, which are further received by the communication interface 112 to generate fused parameter signals. The process involved in the generation of the fused parameter signals has been described in the subsequent sections of the present disclosure. The signal processor/acquisition device 110 generates digitized vibration signals and cooperates with a communication interface 20 112, which is configured receive the digitized vibration signals and the process the input data to compute the fused parameter to indicate the condition of the bearing. In an embodiment, the communication interface includes a computer, a display, and a user interface.
In an embodiment, the communication interface 112 is further configured to 25 transform the vibration signals from time domain into the frequency domain using Fast Fourier Transform (FFT) to generate frequency domain vibration signals. The
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communication interface 112 is further configured to filter out the frequency domain vibration signals in batches of pre-determined frequency ranges to generate filtered vibration signals. In another embodiment, the pre-determined frequency ranges include ranges of 80 Hz to 250 Hz, 250 Hz to 400 Hz, 400 Hz to 1200 Hz, 1200 Hz to 2000 Hz, 2000 Hz to 3500 Hz, and 3500 Hz to 6000 Hz. The communication 5 interface 112 is further configured to transform the filtered vibration signals from frequency domain back into the time domain using Inverse Fast Fourier Transform (IFFT) to generate filtered time domain vibration signals. The communication interface 112 is further configured to fuse the filtered time domain vibration signals to generate the fused parameter. The system 100 of the present disclosure makes use of 10 the baseline data from the machine to account for the variations in the acquired condition data for better assessment of the bearing health. Furthermore, the system 100 filters the acquired data into multiple frequency zones to evaluate the relevant parameters associated with the bearing. This process is more accurate over the existing three band approach. 15
The holding arrangement 104 comprises a pneumatic cylinder 114, and a holding plate 116 connected with a piston rod 114A of the pneumatic cylinder 114, wherein the holding plate 116 is configured to hold the outer ring 101A of the bearing 101 while applying a pre-determined load, via the pneumatic cylinder 114, on the bearing 101. 20
The sensor 108 (also interchangeably referred to as accelerometer 108) is supported within a support structure 118 that comprises a first support frame 118A configured to support the accelerometer 108 and the probe 102. A second support frame 118B is connectable to the first support frame 118A to define a hollow space within which the accelerometer 108 is housed. The second support frame 118B is configured to 25 support a pre-loading arrangement 120 that is configured to apply a pre-load on the accelerometer 108.
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In another embodiment, the pre-loading arrangement 120 comprises a bolt 122, and a spring 124 configured within the hollow space such that a first operative end 124A of the spring 124 is connected to a first operative end 122A of the bolt 122, and a second operative end 124B of the spring 124 abuts the accelerometer 108. A linear bearing 126 is configured on the first support frame 118A to circumscribe the probe 102 and 5 allow longitudinal movement of the probe 102 therewithin. In an embodiment, a cap 128 is mounted on the second operative end 122B of the bolt 122 to facilitate easy rotation of the bolt 122 for the purpose of applying desired pre-load on the accelerometer 108.
Referring to Fig. 2, in accordance with an embodiment of the present disclosure, the 10 first support frame 118A can be further coupled to another auxiliary support frame 152 for the purpose of holding the first support frame 118A in position. The coupling of the first support frame 118A with the second support frame 118B, and the coupling of the first support frame 118A with the auxiliary support frame 152 is achieved via fasteners 154A – 154D. 15
In accordance with a working example of the present disclosure, the acquisition device 110 is National Instrument’s USB based Data Acquisition (DAQ) card that is configured to cooperate with the processing software included in communication interface 112. The vibration signals acquired from the bearings 101 through the accelerometer 108 are digitized using the DAQ card and then the raw time domain 20 data of the vibration signals is processed and analysed using an in-house developed software on the Matlab platform. The dynamic signal acquisition module on the DAQ card does high-accuracy measurements from the IEPE sensors (accelerometer 108). The acquisition channels simultaneously acquire vibration signals at the rates ranging from 1 to 102.4 kS/s. The vibration signal is then sampled by a 24-bit delta-sigma 25 analog-to-digital converter (ADC) that performs digital filtering with a cut-off frequency that automatically adjusts to the set data rate.
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The DAQ card acquires the time domain vibration signals from the bearings. The
acquired time domain data is transformed into frequency domain using Fast Fourier
Transform (FFT). Employing mathematical filters from the MATLAB software, the
desired frequency ranges of interest (80 Hz – 250 Hz; 250 Hz – 400 Hz; 400 Hz –
5 1200 Hz; 1200 Hz – 2000 Hz; 2000 Hz – 3500 Hz; 3500 Hz – 6000 Hz) are filtered
out. The filtered signal is transformed back into the time domain using Inverse Fast
Fourier Transform (IFFT). The root mean square (RMS) value of the filtered time
domain signals are transformed into a dB unit using the following equation:
o
10
G
G
dB  20log where
G = RMS value of acceleration in the given frequency band
Go =10-5g =10-6m/ sec2
ì
í ï
î ï
ü
ý ï
þ ï
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All the extracted parameters from all the six frequency bands are fused to generate a
fused single parameter. An important aspect of the data fusion is that this parameter
systematically accounts for the baseline data from a select sample of the healthy set
of bearings of a given type, so that any new bearing measurement data can be
15 compared with the baseline set. A decision based on multiple parameters increases
the reliability of the bearing condition monitoring system. The fused single parameter
considers the correlation between different parameters and is more robust than simple
addition/multiplication of the extracted parameters. It is used to find out similarity of
a set of values from an unknown sample to a set of values measured from a collection
20 of known samples. These known samples are the perfect/healthy bearings.
The system 100 of the present disclosure is such that it can diagnose the health of a
freshly manufactured bearing as well as used up bearings. The readings obtained by
the accelerometer 108 and the processing performed by the communication interface
112 using the approach of generating the fused single parameter provides for an
25 indication of the health of the bearing 101 while considering different parameters of
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the bearings over six different frequency ranges. Such a comprehensive analysis allows for detecting faults in the newly manufactured bearings as well, which was not possible in the conventional approaches, which only looks for amplitudes of characteristic defective frequencies of the bearing.
TECHNICAL ADVANCEMENTS 5
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a bearing diagnosis system:
 that can diagnose freshly manufactured bearings as well as used/worn out bearings; and
 that is automatic and provides a robust diagnosis of the bearing. 10
 that covers a wide range of bearings. The number of bands and bandwidth of frequency for each band for extracting the energy is decided based scientific data processing of data from a large number of bearings of different types. This process makes the diagnosis of both distributed and localized flaw more robust. 15
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the 20 embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
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The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and 5 range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of 10 the embodiments as described herein.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. 15
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for 20 the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
While considerable emphasis has been placed herein on the components and 25 component parts of the preferred embodiments, it will be appreciated that many
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embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted 5 merely as illustrative of the disclosure and not as a limitation.

WE CLAIM:
1. A bearing diagnosis system (100) comprising:
a probe (102) configured to abut an outer ring of a bearing (101), wherein said outer ring of said bearing is held by a holding arrangement (106), and an inner ring of said bearing is coupled with a motor to facilitate the rotation of said inner ring 5 with respect to said outer ring that is stationary, thereby inducing vibrations within said bearing;
a sensor (108) coupled with said probe, said sensor configured to sense said vibrations and generate vibration signals;
an acquisition device (110) communicatively coupled with said sensor (108) 10 and configured to receive and digitize said vibration signals to generate digitized vibration signals; and
a communication interface (112) cooperating with said acquisition device (110) and configured to receive said digitized vibration signals and process the input data to generate the said fused parameter to indicate the condition of said 15 bearing.
2. The system as claimed in claim 1, wherein said communication interface (112) further configured to: transform said vibration signals from time domain into frequency domain using Fast Fourier Transform (FFT) to generate frequency domain vibration 20 signals; filter out said frequency domain vibration signals in batches of pre-determined frequency ranges to generate filtered vibration signals;
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transform said filtered vibration signals from frequency domain back into the time domain using Inverse Fast Fourier Transform (IFFT) to generate filtered time domain vibration signals and quantify the band vibration energies; and fusing said filtered time domain vibration signals to generate said fused parameter. 5
3. The system as claimed in claim 1, wherein said communication interface (112) includes a display, a computer, and a user interface. 4. The system as claimed in claim 2, wherein said pre-determined frequency ranges include ranges of 80 Hz to 250 Hz, 250 Hz to 400 Hz, 400 Hz to 1200 Hz, 1200 Hz to 2000 Hz, 2000 Hz to 3500 Hz, and 3500 Hz to 6000 Hz. 10 5. The system as claimed in claim 1, wherein said holding arrangement (106) comprises: a pneumatic cylinder (114); and a holding plate (116) connected with a piston rod of said pneumatic cylinder, said holding plate configured to hold said outer ring of said bearing while 15 applying a pre-determined load, via said pneumatic cylinder, on said bearing. 6. The system as claimed in claim 1, wherein said sensor (108) is an accelerometer. 7. The system as claimed in claim 6, wherein said accelerometer is supported within a support structure, said support structure comprises: a first support frame (118A) configured to support said accelerometer and said 20 probe; a second support frame (118B) connectable to said first support frame to define a hollow space within which said accelerometer is housed, said second support frame configured to support a pre-loading arrangement that is configured to apply a pre-load on said accelerometer. 25
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8. The system as claimed in claim 7, wherein said pre-loading arrangement comprises: a bolt; a spring configured within said hollow space such that a first operative end of said spring is connected to a first operative end of said bolt, and a second 5 operative end of said spring abuts said accelerometer. 9. The system as claimed in claim 7, wherein a sleeve bearing is configured on said first support frame (118A) to circumscribe said probe (102) and allow longitudinal movement of said probe (102) therewithin. 10. The system as claimed in claim 8, which includes a cap mounted on a second 10 operative end of said bolt to facilitate rotation of said bolt.