FAULT ANALYSIS IN GEARBOX USING VIBRATION TECHNIQUE Pratesh Jayaswal 1#,Sawan Arya 2#, Nidhi Gupta 3# #1Head of the Department of Mechanical Engineering, Madhav Institute of Technology & Science, Gwalior, M.P, India, #2Research scholars, Department of Mechanical Engineering, Madhav Institute of Technology & Science, Gwalior #3Research scholars, Department of Mechanical Engineering, Madhav Institute of Technology & Science, Gwalior, ABSRACT Gears are important element in a variety of industrial applications such as machine tool and gearboxes. An unexpected failure of the gear may cause significant economic losses. Vibration analysis for condition assessment and fault diagnostics has a long history of application to power and mechanical equipment. This paper deals with gear condition monitoring based on vibration analysis techniques. The detection and diagnostic capability of some of the most effective techniques are discussed and compared on the basis of experimental results, concerning a gear pair affected by a fatigue crack. This paper deals with gear condition monitoring based on vibration analysis techniques. The detection and diagnostic capability of some of the most effective techniques are discussed and compared on the basis of experimental results, concerning a gear pair affected by a fatigue crack. Experiments are carried out using the condition monitoring instrument vibrometer to measure vibration severity for two different conditions of gears. The Peak value of vibration is determined from the experimental analysys, it is found that the vibration level increases for faulty gear as compare to healthy gear. Keywords: Vibrometer, Vibration Analysis, Gearbox, Peak value, Sigma plot Page 566
INTRODUCTION: Machine fault diagnosis is a field of Mechanical Engineering concerned with finding faults arising in machines. A particularly well developed part of it applies specifically to rotating machinery, one of the most common types encountered. To identify the most probable faults leading to failure, many methods are used for data collection, including vibration monitoring, thermal imaging, oil particle analysis, etc. Then these data are processed utilizing methods like spectral analysis, wavelet analysis, waveform analysis (in the time domain, because spectral analysis usually concerns only frequency distribution and not phase information) and others. The physical movement or motion of a rotating machine is normally referred to as vibration, Since the vibration frequency and amplitude cannot be measured by sight or touch, a means must be employed to convert the vibration in to a usable product that can be measured and analyzed. Electronics, Machine, and chemical physics are closely related. Therefore, it would logically follow that the conversion of the mechanical vibration into an electronic signal is the best solution. This paper is focused towards features that are used for the detection of gear faults.here we have used The vibration techniques with two main purposes. The first purpose is to separate the gearbox related signal from other components and to minimize the noise that may mask the gearbox signal, especially in the early stages of the fault. The second purpose is to identify the status of the gearbox, to distinguish the good and the faulty gear and to indicate the defective components EXPERIMENTATION: An experimental test rig with controlled operating conditions was set up to conduct a series of tests using spur gears.the input shaft had 22 teeth while the output shaft had 18 teeth, with a pressure angle of 20 A test was carried out on both gears healthy and faulty. The gearbox was driven by a electric motor. A photograph of the experimental set-up is shown in Fig. 1, and a list of the numbered apparatus is given in Table 1.Measurements were taken at the motor, input and output sides of the gearbox in healthy gear condition and faulty gear condition and comparison were taken among these two condition that how it affect the vibration level. After each data collection, the vibration data was taken, and motor speed values were entered into a spreadsheet. Table 1 Numbered apparatus of the test rig shown in Fig. 1 Number Description 1 1/3kW, single phase electric induction motor 2 Input and output star couplings 3 Gearbox containing two Ronson spur gears 4 centrifugal water pump 5 Motor mounting frame Page 567
1 2 3 4 5 Fig. 1 Experimental setup(number of apparatus given in table 1) Fig. 2 Measured vibration in gear box using healthy gear Measurements were taken at the motor, and input and output sides of the gearbox. The recommended lubricating oil for the gearbox is EP 90 gear oil. Page 568
Fig. 3 Gearbox having healthy gear Fig. 4 Faulty gea DATA COLLECTION: Data has been collected from the experiment setup of gear fault detector machine in which two different condition of gears healthy and faulty is determined by taking the peak value of vibration with the help of vibrometer.the vibration analysis spectra obtained from the tests were compared in order to determine the effectiveness of each condition in fault detection for various gear faults. Table-2: HEALTHY GEAR CONDITION S. no. Duration (Hr) Input shaft speed in rpm Output shaft speed in rpm cceleration (m/s 2 ) Rms value (m/s 2 ) 1 1 1474 1801 0.13 0.41 2 2 1485 1809 0.14 0.54 3 4 1476 1802 0.19 0.73 4 6 1486 1822 0.18 0.63 5 8 1485 1813 0.16 0.56 6 11 1475 1747 0.17 0.58 7 13 1473 1804 0.16 0.53 8 15 1478 1801 0.17 0.75 9 18 1477 1812 0.18 0.69 10 20 1480 1805 0.15 0.72 11 22 1488 1803 0.19 0.66 12 25 1475 1806 0.17 0.59 13 28 1477 1801 0.16 0.61 14 32 1472 1798 0.18 0.67 15 34 1470 1807 0.17 0.70 16 36 1473 1806 0.18 0.72 Page 569
Table-3: FAULTY GEAR CONDITION S. no. Duration (Hr) Input shaft speed in rpm Output shaft speed in rpm (m/s 2 ) Rms value (m/s 2 ) 1 1 1482 1813 0.19 1.41 2 2 1481 1788 0.18 1.74 3 4 1480 1817 0.18 1.46 4 6 1481 1789 0.18 1.47 5 8 1478 1806 0.19 1.80 6 10 1488 1816 0.20 1.49 7 12 1481 1808 0.18 1.74 8 14 1476 1809 0.19 1.64 9 16 1479 1810 0.19 1.49 10 20 1483 1808 0.18 1.59 11 24 1478 1815 0.19 1.68 12 28 1480 1809 0.18 1.67 13 32 1483 1813 0.20 1.73 14 36 1479 1818 0.19 1.72 15 40 1486 1814 0.18 1.70 16 44 1485 1815 0.20 1.74 RESULT AND DISCUSSION:- The vibration phenomenon for gearbox has been analyzed by plotting the graph for healthy gear condition and faulty gear condition.the plan of the experiment was developed to assess the effect of faulty gear in gearbox by vibration analysys in gearbox. Table 1 illustrates the experimental result of vibration in healthy gear condition. Table 2 illustrates the experimental result of vibration in faulty gear condition. Fig 1 shows the vibration level in healthy gear condition, Fig 2 shows the vibration level in faulty gear condition, Fig 3 Shows the comparison of vibration level in healthy gear and faulty gear in gearbox. All the graphs are plotted by using sigma plot software. To investigate the effectiveness vibration analysis in the diagnosis of spur gear faults resulting from (i) healthy gear condition and (ii) faulty gear condition. The vibration analysis spectra obtained from the tests were compared in order to determine the effectiveness of each condition in fault detection for various gear faults. Many types of defects or damage will increase the machinery vibration levels. These vibration levels are then converted to electrical signals for data measurement by accelerometers. Page 570
0.8 0.7 (m/s2) 0.6 0.5 0.4 0.3 0 10 20 30 40 50 60 Time in hour Time vs acceleration in healthy gear Fig 1 1.9 1.8 1.7 (m/s2) 1.6 1.5 1.4 1.3 0 10 20 30 40 50 60 Time in hour TIime Vs acceleration in faulty gear Fig 2 Fig 2 Page 571
2.0 1.8 1.6 1.4 (m/s2) 1.2 1.0 0.8 0.6 0.4 0.2 0 10 20 30 40 50 Time in hour Time vs accleration in healthy gear Time vs acceleartion in Faulty gear Fig 3 CONCLUSION:- In this study of healthy gear and faulty gear conditions being imposed onto a spur gearbox system, the vibration analysis technique concerning the resulting gear faults was found to be very good. This technique added more evidence to complete a diagnosis of the gearbox system, which proved to be correct upon inspection of the gearbox. The detection strengths of vibration analysis were found to be in the detection of fault conditions in gearbox using spur gear. From the graph it is concluded that in faulty gear condition the peak value of acceleration which is vary between 1.41-1.80 m/s 2, which is more than peak value of acceleration in healthy gear condition (0.41-0.75 m/s 2 ). Vibration is highly raised in faulty gear hence it is easily found fault in gearbox. REFERENCES:- [1] Polyshchuk V.V et al (2002), Gear fault detection with time frequency based parameter NP4, International Journal of Rotating Machinery 8(1),pp 57-70 [2] Choy F. K et al,(2003), Damage Identification of a Gear Transmission Using Vibration Signatures, Journal of Mechanical Design, Vol. 125,pp.394-403 Page 572
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