UNDERSTANDING VIBRATION ANALYSIS In （理解振动分析）.pdf

Understanding Vibration Analysis Vibration analysis is a useful method of performing all of the following: evaluating current machine condition diagnosing faults associated with operational machines monitoring and trending the overall condition of machines over time. A complete vibration analysis consists of three distinct components: absolute vibration measurements bearing condition measurements FFT frequency analysis The initial measurements, absolute vibration measurements, are an important indicator of the current state of a machine. They can be measured quickly and easily and have been successfully used for decades for the evaluation of overall machine condition. In order to standardize methods of measurement and facilitate comparison of data, a number of national and international guidelines have been established and are currently in practice. Since 1964, VDI guideline 2056 has served as the basis of several standards regarding execution of the measurements, selection of the measuring points and limits of evaluation. In accordance with VDI 2056, the standard vibration measurement is the root mean square (rms) value of the vibration velocity measured in the frequency range of 10 to 1,000 Hz (1 Hz is one cycle per second). This same guideline specifies that the measurements should be preferably taken at the bearings of the machine in the following six locations: 1 drive end horizontal 2 drive end vertical 3 drive end axial 4 outboard horizontal 5 outboard vertical 6 outboard axial To evaluate the vibration level, the largest amplitude of the 6