Vertical versus horizontal rotors dynamics and diagnostics

Abstract

The development of modern rotating machines the need for effective methods of diagnostics has arisen. As the size of the machinery constantly reduces, it is crucial to develop effective methods for evaluation of technical conditions not only for the entire rotating system, but for each damaged element, such as antifriction and journal bearings, couplings, gears, etc. The optimization of rotating system goes through theoretical modelling based on FEM, bond graph theory, prototyping and experimental vibration testing in laboratories and machines in situ. Nodal defects should be discovered in early stage of their development. This article describes the diagnostic studies of rolling bearing faults in horizontal and vertical rotor systems that were performed at the specially designed research bench. The research bench is composed of a rotor with a disc with the changeable excitation mass fixed on it, rotor driven by asynchronous AC motor controlled by frequency inverter. Rotor, mounted in supports, using single row deep groove ball bearings 6004, class C3. During the research first and second non-defected, rolling bearings were replaced with rolling bearing with inner and outer ring race defects. Experiments conducted by changing the rotor axis of rotation from vertical to horizontal. Experiments were performed with permissible imbalance (according to ISO 1940-1) with maximum allowable imbalance and with more than 2 times higher than permissible, assessing the level of allowable imbalance magnitude according to standard G6.3 class for rotary systems with flywheel impeller. Measurements of mechanical vibration acceleration measured with a 4 acceleration transducers, mounted on the supports. This article focused on statistical analysis of the measured transducers data. New statistical parameter, “Ratio of bearing defect visibility (RBDV)” designed. [...]