Title of the Invention

"Histogram based Vibration signature analysis for the detection of Ball bearing defects"

Fieldof Invention DSP based method of Electronics and communication Engineering applied for Mechanical failure of Bearings. Give clear idea about the deterioration of the failure of bearing and to set the threshold valué for the preventive maintenance / Replacement of Ball bearing in order tó reduce the down time in Industrial environment.

Use of the Invention In diagnosing the fault of ball bearings based on vibration signature this method is an effective method for extracting the fault features. Based on the histogram analysis, the fault features based bn the growth of the amplitude, the exact nature of the failure can be identifled. This is useful in diagnosing and preventing the failures in the bearing etc.

Abstractof the Invention The diagnosis/prognosis of deterioration ball bearing 4n machineries is an important feature. Normally the signature of the failures are weak and are often buried with the noise. Extraction of fault signatufe is a tedious task in the prognostic methods of finding the failures of bearing. The Fast Fourier transform (FFT) based method is often used for detection of the deterioration and failures in bearing under fault as well as in good condition which are acquired anyon of the three axes of the central shaft. Tnis present method produces múltiple peaks for bearings with defects such as inner race and outer race wear and tear. ball failures and contamination of working área.

Apparatus used for invention

l.Ball bearing, 2. Electric motor,3. Vibration Sensor,4. External Charge to Vóltage converter, 5. Coaxial RG188 Standard cable,6. Micro dot connectors, 7.BNC Connectors, 8.PCB 481 A Vibration Signal Conditioner, 9.Bearing Housing, lO.Prófile meter, ll.High Speed Data acquisition system (20 kS/s), 12.Labview based Data analysis.

Surface defect and Frequency

The present method excites the bearing in the following frequencies when put to vibration. A bearing contains 4 major parts i.e. inner raceway, outer raceway, Rolling element and cage. The contributors of the vibration frequency involve inner raceway,outer raceway and the rolling element on running the central shaft. Maintaining the integrity of the specifications of the bearing, is a major operation related to a particular machine. Henee there are five combinations of frequencies possible. Generally, as the level of modulation increases the sideband also increases. As the number of defect increases more side bands are generated.

Defect free bearing

Rolling contact bearings represents complex vibration system whose components are rolling elements, inner race , outer race and the cage interact to genérate vibration signatures. Now a days, the bearings are manufactured with high precisión and the defeets are at the level of nano meters. Though, the vibration is produced in the audible level, the defect free or minimum defective bearing will generates a central frequency and the sidebands are around the central amplitude. Henee, such bearings with minimum level óf defeets produces a single peak in the histogram.

Surface fínish Vibration Signature

Surface roughriess is a significant factor that contributes to the vibration level of the roller bearing, When the thickness of the lubrication in the ball bearing is very thin and it encounters asperities in the surface of the ball bearing which come into contact with the bearing metal part of the raceways resulting in the high level of vibration. Such kind of vibration is, random sequence of small impulses which excite all the natural modes of the bearing. Henee the amplitude contfibuted by such a bearing is distributed everywhere.

Effect of imperfection in the balls

Defects in the rolling of ball element can genérate a frequency at twice the ball spin frequency. When the defect of the ball is oriented in the axial direction it will.not come into contact with the inner and outer racewayand henee there are difficulties to.detect. If more number balls are defective, manifesting the sums of the ball spin frequency can be generated.

Histogram anaíysis of data

The technique for, the detection of the failures in the ball bearings, calculates the discrete histogram results which runs continuously and accumulates, the data from all the input signáis. The histogram is the graphical representaron of amplitude distribution. We have localized the fault on the inner or outer race of the ball bearing in which the time scale causes the series of impulses. It relates to the relative speed and the load between the bearing as well as the dimensión of the ball bearing.

Indication of the failure

Imbalance createdin the inner and outer race of the defect free bearing is of very less. The amplijt.ude is excitéd in a single pattern around the main pattern henee the side bands are also is in the same range. Henee by having a single spectrum in the histogram implies the better energy transfer to the payload from the motor, When the bearing is with imperfections in the outer race, inner race and balls etc, it generates múltiple amplitudes henee accordingly the frequency spread also be wide. Henee by identifying the RPM and various characteristics of the histogram spread of various amplitudes can clearly be identified.

Advantage of this method

The deterioration of the bearing involves the factors by the combination of inner raceway, outer raceway, balls, contamination etc. The FFT method gives existing frequencies and the side bands. Whereas this histogram analysis will provide the amplitude variation in the time domain.

1. Diagnosis based on the time domain data with amplitude henee we get a clear repre$entation of the múltiple faults present in the bearing.

2. The overall view Óf the factors contributing the amplitude can be identified. By setting the threshold valué for a particular defeetthe preventive maintensíice can be initiated for the fault diagnosis.

Claim on this invention

I/We Claim that the Histo.gram based vibration data analysis for the detection of Bearing faults is.the First kind of analysis explored. As this is the analysis of Statistical náture with industrial application. The act of the following leads to infringement or unauthorised use of our invention.

(1) This invention is applicable to any number of balls linked with outer^ race, inner race and the cage is fully covered in out invention.

(2] T,he use of . Histogram based analysis for the cíetectiQñ/assessment of detorioration level in the outer race ofball bearing in the commercial application.

(3} ,The use of Histogram based analysis for the detection/assessment of detorioration level in the inner race of hall bearing in the commercial application.

(4) The , use of Histogram based analysis for the 'detection/assessment of detorioration level in the cage of ball bearing in the commercial application.

(5) The 'use of Histogram based analysis for the detection/assessment of detorioration level in the balls/roliing element of ball bearing in the commercial application,

(6) Use of. this statical method for detection, assessment of detorioration level and arrival of threshold valúes in the industriáí/commercial establishments leads to unauthorised use of our invention and claim of liability and lósses as'per the Indian/International Patent act/Treaties.