Analysis of Faulty Vibration by Three-Dimensional Information

Abstract

Some kind of machine faults such as unbalance, misalignment, looseness, and eccentricity occupy the most part of the category of fault of structure. It is important to diagnose these faults accurately to prevent the recurrence of the same fault. The unbalance includes static unbalance, couple unbalance, quasi-static unbalance and dynamic unbalance. The misalignment includes parallel misalignment and angular misalignment. In any fault of structure, vibrations both perpendicular and parallel to the rotation shaft occur, and the diredional characteristics of vibration change with the type of machine fault. If we measure vibrations in three directions by a conventional unidirectional type of vibrometer, the measured data does not include enough information for diagnosis. It is extremely difficult to diagnose the fault of structure accurately only by this information. lt is necessary to observe and analyze the movement of measured point in order to diagnose the fault and search its causes by using three directional information processing technology that measures orthogonal three directional vibrations simultaneously and uses the phase information among them. To realize it, the analysis technique of vibration information in 3-dimensional space is necessary. In this paper, we describe a new hand-held type triaxial vibrometer and its pickup. The operation principle is quite different from conventional triaxial pickups. A detailed operation principle of the new pickup is reported. Finally we propose new display method and data processing technique of vibration in 3-dimensional space.