Rolling body damage When the bearing rolling body damage, such as flaking, cracks, pitting, etc., the defect site through the inner ring or outer ring raceway surface will have impact vibration. When there is no radial clearance in the rolling bearing, an impact vibration of frequency nZfb (n = 1, 2, ...) is generated. Usually, the rolling bearing has a radial clearance. Therefore, as in the case of pitting corrosion in the inner ring, the amplitude modulation may occur depending on the position where the pitting site collides with the inner ring or the outer ring, but in this case The amplitude modulation is performed at the revolution frequency fc of the rolling element. At this time the vibration frequency nzfb disabilities fc. The so-called precision diagnostic method of rolling bearings, is the use of simple diagnosis method to determine the bearing has failed, to further determine the type of fault and the site of occurrence in order to take appropriate measures. Precise diagnosis of rolling bearings and rotating machinery, reciprocating machinery and other precision diagnostics, the main use of spectrum analysis. Because the vibration frequency of rolling bearing components is very rich, both contains low-frequency components, but also contains high-frequency components, and each specific fault corresponds to a specific frequency component. Before spectrum analysis, we need to separate the specific frequency components by appropriate signal processing methods, then perform absolute value processing, and finally perform frequency analysis to find out the characteristic frequency of the signal and determine the location and category of the fault. Bearing inner raceway Damaged bearing inner raceway damage, such as: flaking, cracks, pitting, etc., if the radial clearance of the rolling axis, it will produce the frequency of nZfi (n = 1,2, ...) shock vibration. Rolling body damage Vibration: bearing eccentricity When the inner ring of the rolling bearing appears serious wear and the like, the bearing may be eccentric. When the shaft rotates, the shaft center (inner ring center) will swing around the outer ring center. At this time, the vibration The frequency is nf r (n = 1, 2, ...). Damage characteristics of the inner raceway vibration Usually rolling bearings have radial clearance, and the unilateral load, according to the pitting portion of the rolling contact with the impact of the different positions, the amplitude of the vibration amplitude cyclical changes occur that amplitude modulation occurs . When the amplitude is modulated at the shaft rotation frequency f, the vibration frequency at this time is nzfi = fr (n = 1, 2, ...); if the amplitude modulation is performed at the revolution frequency of the rolling element (ie, the cage rotation frequency) The vibration frequency is nZfi ± fc (n = 1,2, ...). Bearing outer raceway damage When the outer raceway bearing damage, such as spalling, cracking, pitting corrosion, etc. (Figure 2), the rolling body will pass when the impact vibration. Since the relative position between the pitting location and the load direction is constant, there is no amplitude modulation at this time. The vibration frequency is nZfo (n = 1, 2, ...).
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