• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1996년도 제24회 추계학술대회
• /
• pp.207-212
• /
• 1996

The shotpeening treatment were conducted for improving the strength of rolling contact fatigue of machine element like a gear. This paper was undertaken to analyze the influence of shotpeening treatment for inner race of ball bearing on the roiling contact fatigue. Shotpeening treatment were applied to the full hardened and the carbonitrided bearing. And the rolling contact fatigue life test and X-ray diffraction test were carried out. The results of this study showed that the fatigue life of ball bearing in the clean and the contaminated oil could be improved by shotpeening treatment. This effect was found to be more pronounced to the full hardened bearing.

• 조명전기설비학회논문지
• /
• 제19권6호
• /
• pp.36-45
• /
• 2005

이 논문은 다른 종류의 유도전동기 구름베어링 손상을 유도전동기 고정자 전류신호해석을 통하여 검출하고 실시간으로 손상을 진단하는 알고리즘을 개발하였다. 유도전동기 구름베어링의 손상을 검출하기 위하여 정상적인 베어링을 갖는 유도전동기, 측정열에 불량을 가지고 있는 전동기와 베어링 외륜에 구멍을 가지고 있는 2가지 종류의 비정상 베어링을 갖는 유도전동기 3set를 실험시스템을 구축하였다. 또한 유도전동기의 구름베어링시스템의 비정상적인 상태에서 고정자전류을 검출하기 위하여 TMS320F2407 DSP 칩을 이용하여 데이터 획득보드를 개발하였다. 이 고정자전류신호를 해석을 통하여 베어링 손상을 검출하기 위한 방법으로 FFT, 웨이브렛 분석 및 내적에 의한 평균 신호패던에 의한 분석결과를 제시하였다. 특히 내적에 의한 신호분석 온 통하여 베어링 손상 여부를 실시간으로 진단할 수 있는 새로운 알고리즘과 분석방법을 제시하였다.

• 한국소음진동공학회논문집
• /
• 제22권12호
• /
• pp.1227-1236
• /
• 2012

The low speed machinery faults are usually caused by the bearing failure of the rolling elements. As the life time of the bearing is limited, the condition monitoring of bearing is very important to maintain the continuous operation without failures. A few monitoring techniques using time domain, frequency domain and fuzzy neural network vibration analysis are introduced to detect and diagnose the faults of the low speed machinery. This paper presents a method of fault detection for the rolling element bearing in the low speed machinery using the Wiener filtering and shock pulse counting techniques. Wiener filter is used for noise cancellation and it clearly makes the shock pulse emerge from the time signal with the high level of noise. The shock pulse counting is used to determine the various faults obviously from the shock signal with transient pulses not related with the bearing fault. Machine fault simulator is used for the experimental measurement in order to verify this technique is the powerful tool for the low speed machine compared with the frequency analysis. The test results show that the method proposed is very effective parameter even for the signal with high contaminated noise, speed variation and very low energy. The presented method shows the optimal tool for the condition monitoring purpose to detect the various bearing fault with high accuracy.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 춘계학술대회논문집
• /
• pp.324-328
• /
• 2007

Vibration monitoring of rolling element bearings is probably the most established diagnostic technique for rotating machinery. Acoustic Emission (AE) Analysis is an extremely powerful technology that can be used within a wide range of applications of non destructive testing. Therefor, this paper investigates the detection methods using AE for rolling element bearings about low-speed. Two transducers, the accelerometer and acoustic emission sensor, are used to acquire data and the results are compared for the capacity of early fault detection.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1996년도 제23회 학술대회
• /
• pp.53-59
• /
• 1996

The new trends in main spindle design of Machining Center are focused on high-speed, high-precision and high-stiffness. As a main spindle bearing, the angular-contact ball bearing is well used. A rolling bearing is usually only a small part of a larger mechanical system, but its performance can have a great influence on the functioning of the whole machine. This work is about fatigue life tester design and monitoring of defected rolling-element bearings. The major work is done via experiments and the vibration signal is analysised by means of frequency spectrum technique. By analyzing the frequency spectrum, it is possible to view the condition of the bearings.

• 한국기계가공학회지
• /
• 제16권4호
• /
• pp.38-45
• /
• 2017

A finite element analysis-based approach which investigates the causes of the breakdown in the outer ring of the choke at hot rod rolling mill is presented. Two-dimensional drawings of the whole vertical-type mill stand are transformed into three-dimensional CAD models. Non-linear elasto-plastic deformation analysis of material at the roll gap is performed for computing roll force and torque of the work roll. Then, the reaction forces of the bearing rings together with a set of roller bearings that support the work roll are obtained by means of rigid body motion analysis. Finally, stress behaviors in the bearing rings together with a set of roller bearings that support the work roll are investigated by linear elastic analysis. Results reveal that stress at the contact area between the outer ring and roller bearing is extraordinary high when an internal gap between an external surface of the outer ring and the internal surface of the chock due to wear of the inside of the chock occurs.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.585-590
• /
• 2004

Many machine failures are not detected well in advance due to the masking of background noise and attenuation of the source signal through the transmission mediums. Advanced signal processing techniques using adaptive filters and higher order statistics have been attempted to extract the source signal from the measured data at the machine surface. In this paper, blind deconvolution using the eigenvector algorithm (EVA) technique is used to recover a damaged bearing signal using only the measured signal at the machine surface. A damaged bearing signal corrupted by noise with varying signal-to-noise (s/n) was used to determine the effectiveness of the technique in detecting an incipient signal and the optimum choice of filter length. The results show that the technique is effective in detecting the source signal with an s/n ratio as low as 0.21, but requires a relatively large filter length.

• 대한기계학회논문집A
• /
• 제24권7호
• /
• pp.1740-1747
• /
• 2000

Under repeated rolling, initial plastic deformation introduces residual stresses which render the steady cyclic state purely elastic. This is called the process of shakedown. Many studies have been done about the shakedown in semi-infinite half space using calculated Hertizian pressure. In this paper shakedown processes in a shaft are studied by finite element analyses of a two dimensional(plane strain) model with elastic-linear-kinematic-hardening-plastic material subjected to repeated, frictionless rolling contact. Symmetric and non-symmetric pressure distributions are obtained using a simplified model of the bearing-shaft assembly. The rolling contact is simulated by repeatedly translating both pressure distributions along the surface of the shaft. By the influence of the non-symmetric pressure, larger residual radial tensile stress is generated in the immediate subsurface layer, which may make a crack propagate and, the subsurface undergoes a zigzag plastic deformation during the shakedown process, which may lead to a crack initiation.

• Journal of Advanced Marine Engineering and Technology
• /
• 제33권5호
• /
• pp.672-678
• /
• 2009

Acoustic Emission (AE) technique is a non-destructive testing method and widely used for the early detection of faults in rotating machines in these days, because the sensitivity of AE transducers is higher than normal accelerometers. So it can detect low energy vibration signals. The faults in the rotating machines are generally occurred at bearings and gearboxes which are the principal parts of the machines. It was studied to detect the bearing faults by envelop analysis in several decade years. And the researches showed that AE had a possibility of the application in condition monitoring system(CMS) using the envelope analysis for the rolling bearing. And peak ratio (PR) was developed for expression of the bearing condition in condition monitoring system using AE. Noise level is needed to reduce to take exact PR value because the PR is calculated from total root mean square (RMS) and the harmonics peak levels of the defect frequencies of the bearing. Therefore, in this paper, the discrete wavelet transform (DWT) was added in the envelope analysis to reduce the noise level in the AE signals. And then, the PR was calculated and compared with general envelope analysis result and the result of envelope analysis added the DWT. In the experiment result about inner fault of bearing, defect frequency was difficult to find about only envelop analysis. But it's easy to find defect frequency after wavelet transform. Therefore, Envelop analysis added wavelet transform was useful method for early detection of default in signal process.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.539-544
• /
• 2004

This paper discusses the measurement of tire driving performance for 2 types of tire model. Tire is almost composed of rubber, and this is related with the bearing capacity of tire due to the external force. In this study, an explicit time integration method has been used to simulate steady state rolling along a straight path and over a cleat. And analysis for tire dynamic response rolling over a cleat is importnat to study automobile NVH properties. Besides, the evaluation of contact shear force is perfomed for steady state rolling and braking state. The results show that there are noticeable differences between 205/60R15 and 225/60R15 tire model.