• Title/Summary/Keyword: Bearing wear monitoring

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The Early Detection of Journal Bearing Failures by a Pattern Recognition of Ultrasonic Wave (초음파의 형상인식법을 이용한 저널베어링의 마멸파손 검지)

  • 윤의성;손동구;안효석
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.8
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    • pp.2061-2068
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    • 1993
  • Condition monitoring technology is of great importance for the maintenance of complex machinery in view of its early monitoring of the abnormal condition and the protection against failure. Several methods have been used for the detection of failure of journal bearings, one of the main elements of mechanical system. The methods most frequently used are vibration and temperature monitoring, but these are unable to monitor the wear conditions exactly. In this study, an ultrasonic measument method, one of the non-destructive testing methods, was introduced as the monitoring technology. Furtermore a pattem recognition method was applied to analyze the ultrasonic signal. The monitoring system using the pattern recognition method is composed of digital signal processing units and uses Hamming net algorithm for the recognition of ultrasonic waves. From the journal bearing wear test, the occurrence of adhesive wear of the white metal in rubbing contact with the shaft was exactly detected by this system, and the wear status of the journal bearing was monitored by measuring the wear thickness.

Vibration Characteristics According to Wear Progress of Ball Bearings (볼 베어링의 마멸 상태에 따른 진동 특성의 변화)

  • Cho, SangKyung;Park, JoungWoo;Cho, YonSang
    • Tribology and Lubricants
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    • v.33 no.4
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    • pp.141-147
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    • 2017
  • The vibration data of bearings are very useful for monitoring and determining the condition of the bearings. The defect frequencies of ball bearings have been used for monitoring there condition. However, it is not easy to verify the defect frequencies as the wear progress. Therefore there is a need for an easy method to monitor the damages of bearings in real-time and to observe the variations in vibration characteristics as the wear progress. In this study, a bearing test equipment is constructed to diagnose the damage of bearings. The friction coefficient and vibration data are measured by using a torque sensor and an acceleration sensor, and the correlation between the measured data is analyzed to diagnose the condition of the bearing. We reached the following conclusions from the results. When the ball surface, inner and outer rings of a ball bearing are damaged, the friction coefficient increases to over 0.02 with an adhesion on the surface. Moreover this damage occurs more quickly with an increase in the number of revolutions. In the vibration characteristics, the amplitude of vibration wave appears high with an increase in the friction coefficient. In the high frequency range between 1000 and 2000 Hz, a wide range of frequency components with high amplitude occurs continuously irrespective of the number of revolutions.

Thermohydrodynamic Analysis and Pad Temperature Measurement of Tilting Pad Journal Bearing with Worn Pad (표면이 마모된 틸팅 패드 저널베어링의 열윤활 해석 및 온도 측정)

  • Lee, Donghyun;Sun, Kyungho;Kim, Byungock;Kang, Donghyuk
    • Tribology and Lubricants
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    • v.33 no.4
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    • pp.134-140
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    • 2017
  • With the increase in adoption of tilting pad journal bearings (TPJBs), various failure mechanisms related to TPJBs have been reported, of which pad wear is a frequently reported one. Pad wear causes change in geometry of the bearing, which can sometimes result in the failure of the entire system. The objective of this research is to investigate the influence of pad wear on the pad temperature, which is one of the widely used condition monitoring methods for TPJBs. For the theoretical investigation, thermohydrodynamic (THD) analysis was conducted by solving the generalized Reynolds equation and the 3D energy equation. The results of the analysis show that the temperature of the loaded pad increases while that of the unloaded pad decreases, when there is wear on the loaded pads. In addition, the minimum film thickness decreases with an increase in the wear depth. A validation test was conducted with a test rig, which mimics the axial turbine when a test rotor is supported by two TPJBs. The test bearing consists of five pads with a diameter of 60 mm, and a resistance temperature detector (RTD) is installed in the pad for temperature monitoring. The test was performed by replacing the two loaded pads with the worn pad. The test result for the TPJB with wear depth of $30{\mu}m$ show that the temperatures of the loaded pads are $8^{\circ}C$ higher and that of the unloaded pad is $2.5^{\circ}C$ lower than that of the normal TPJB. In addition, the predicted pad temperature shows good agreement with the measured pad temperatures.

An Experimental Study on the Wear and Vibrational Characteristics of a Loosely supported proceeding Bearing (헐겁게 지지된 저널베어링의 마모 및 전동특성 실험적 연구)

  • Chang, Rae-Hyuk;Pyun, Sung-Kwan;Yoon, Eui-Sung;Kong, Ho-Sung;Choi, Dong-Hoon
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.05a
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    • pp.53-62
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    • 2002
  • Condition monitoring plays a vital role since it sustains reliable operation of industrial plants and machinery in the pursuit of economic whole life operation. In order to achieve this goal, it is needed to monitor various parameters of mechanical system such as vibration, wear, temperature and etc., and finally to diagnosis the root causes of any possible abnormal machine condition. In this work, a machine failure caused by mechanical looseness was experimentally simulated and on-line measurement of the vibration, wear and temperature were simultaneously measured. For the quantitative analyses of machine wear, several statistical parameters of the wear particle size distribution were obtained through the center moment method of the Weibull distribution function, and they were compared to vibrational characteristics. Results showed that the wear and vibrational characteristics did not reveal a strong correlation each other in a loosely supported proceeding bearing.

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Diagnosis of a Journal Bearing Fault via Current Signature Analysis (전류신호 분석을 통한 저널베어링 이상상태 진단)

  • Park, Jin-Seok;Huh, Hyung;Jeong, Kyeong-Hoon;Lee, Kyu-Mahn;Park, Keun-Bae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.119-122
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    • 2005
  • A study on motor current signature analysis has been executed for monitoring the fault of journal bearing due to wear. The air gap eccentricity of motor produces specific frequencies in motor current, the supplied current frequency plus and minus rotational rotor frequency. The air gap eccentricity is simulated by the clearance of Journal bearing. The amplitudes of the specific frequencies increase with the increasing clearances. The amplitudes of the specific frequencies continue to increase over the wear limit that is used in the manufacturer of the test motor. Though clear relations between the amplitudes of the specific frequencies and the clearances are not obtained in this paper, the specific frequencies can be used as an indicator of a journal bearing fault. Further study is necessary to make out the quantitative relations between the specific frequencies and the clearances.

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Marine Engine Wear Diagnosis and Assessment Using the Wavelet Transform (웨이블릿을 이용한 선박 엔진 마모 상태 진단 평가)

  • Kim, Kyung-Hwan;Jo, Jae-Han;Lee, Hyun;Lee, Jang-Myung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.6
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    • pp.845-850
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    • 2012
  • Currently power of the diesel engine is increasing continuously, where the wearing problems become more severe. The wearing happens irregularly inside the cylinder, which causes a high burden to the marine engine. In this paper, a novel scheme to measure the wearing and to represent the engine states has been proposed. To monitoring the states of the marine engine efficiently, a laser displacement sensor has been utilized to measure the wearing happening inside the marine engine. To eliminate the noise signals in the distance measurement, the wavelet transform has been adopted, which is robust against the noises caused by vibrations. An engine simulator is designed to develop the system for measuring the engine wears, where the superiority of the wavelet transform against the conventional filtering schemes has been demonstrated.

Application of Hidden Markov Model Using AR Coefficients to Machine Diagnosis (AR계수를 이용한 Hidden Markov Model의 기계상태진단 적용)

  • 이종민;황요하;김승종;송창섭
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.1
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    • pp.48-55
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    • 2003
  • Hidden Markov Model(HMM) has a doubly embedded stochastic process with an underlying stochastic process that can be observed through another set of stochastic processes. This structure of HMM is useful for modeling vector sequence that doesn't look like a stochastic process but has a hidden stochastic process. So, HMM approach has become popular in various areas in last decade. The increasing popularity of HMM is based on two facts : rich mathematical structure and proven accuracy on critical application. In this paper, we applied continuous HMM (CHMM) approach with AR coefficient to detect and predict the chatter of lathe bite and to diagnose the wear of oil Journal bearing using rotor shaft displacement. Our examples show that CHMM approach is very efficient method for machine health monitoring and prediction.

Effect of Surface Roughness of Counterface on Tribological Characteristics of PTFE and UHMWPE (상대재료의 표면거칠기에 따른 PTFE와 UHMWPE의 마찰 및 마멸 특성)

  • Dong, Sun;Chung, Koo-Hyun;Lee, Kyung-Sick
    • Tribology and Lubricants
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    • v.27 no.6
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    • pp.293-301
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    • 2011
  • Understanding of the tribological characteristics of polytetrafluoroethylen (PTFE) and ultra-high-molecular-weight polyethylene (UHMWPE) is crucial for their applications such as bearing and total joint replacement. In this work, the effect of the surface roughness of carbon steel on the tribological behaviors of PTFE and UHMWPE was experimentally investigated by using block-on-ring tribotester with friction force monitoring capability. It was found that that the amount of material transfer layers of PTFE formed on the carbon steel was significantly larger than those of UHMWPE, which was responsible the lower friction coefficient of PTFE. It was also concluded that the effect of surface roughness of carbon steel on the friction coefficient of UHMWPE was more significant than that of PTFE. For UHMWPE, it was found that the effect of surface roughness of counterface was varied with respect to applied normal force and sliding as well. Based on Archard's wear law, the wear coefficient of PTFE and UHMWPE was calculated to be $3{\times}10^{-5}$ ~ $8{\times}10^{-5}$ and $7{\times}10^{-6}$ ~ $2{\times}10^{-5}$, respectively.

Degradation characteristics of pumps in nuclear power plants (원전 펌프의 성능저하 특성)

  • Lee, D.H.;Park, S.G.;Hong, S.D.;Lee, B.H.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.593-598
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    • 2008
  • In the present study, degradation characteristics of pumps in nuclear power plants were investigated to provide the information of degradation mechanism and stressors. The failure records of pumps for the periods 2000 to 2006 on INPO(Institute of Nuclear Power Operations) EPIX(Equipment Performance and Information Exchange System) DB were reviewed. The 1,834 failure records reveal that the critical areas of pump failures are bearing, mechanical seal, gasket/o-ring, shaft, impeller, coupling and packing. Based on the failure rate of critical areas, the important degradation mechanism and stressors were determined. Additionally, the relationship between degradation mechanism and stressors such as wear was examined. Finally, the monitoring parameters related to degradation and stressors were discussed for the future development of degradation evaluation and prognosis technology of pumps.

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Design of Marine Engine Bearing Wear Monitoring and Forecasting System (선박엔진용 베어링 마모도 예측 및 모니터링 시스템 설계)

  • Yang, Jae-Gun;Lee, Sang Yoon;Bae, Jung Hyun
    • Proceedings of the Korea Information Processing Society Conference
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    • 2013.11a
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    • pp.33-36
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    • 2013
  • 운항하는 선박의 특성상 미래 상태를 반영한 예방정비는 선박의 안전한 운항과 운영비용 절감에 중요한 요인이다. 이에 본 논문에서는 선박 엔진의 세 가지 주요 베어링의 마모 상태를 모니터링하고 앞으로의 마모 정도를 예측하는 시스템을 설계하였다. 목표하는 시스템은 현재의 BDC(실린더 하사점) 레벨 데이터 뿐만 아니라 취득한 BDC 레벨 데이터를 시계열 모형으로 예측한 미래값도 보여줄 수 있어야 한다. 이를 위하여 BWM(베어링 마모도 모니터링)의 프로토타입을 제작하고 이 장치로부터 BDC 레벨 데이터를 취득하였다. 이 과정에서 예측한 BDC 레벨과 실측 데이터를 비교해서 시계열 모형을 이용한 마모도 예측 방법이 적용 가능함을 확인하였다.