Elaboration of forecasting methods of analysis of metallurgical facilities electric drives technical state

To prevent losses of equipment downtime, analytical algorithms and data of automated control systems sensors are used to estimate time to the equipment failure approach. It was shown that modern technical systems, such as automated electric drives are equipped by measuring devices which allow to accomplish self-diagnostic of the system in real time mode at existing methods of data processing and analysis. This approach is more effective than traditional methods of diagnostic and does not include additional capital expenses for specialized diagnostic equipment and personal qualification. Hypothesis of forecasting of electromechanical driving system state was elaborated and checked for continuous rolling mill runaway roller, based on character of loading modes by using only one parameter – the electric motor current. Based on the data analysis of wide strip rolling mill 2000 runaway rollers operation, normalized curves of distribution of average values of the runaway roller drive current at its normal operation and origination of a malfunction were built. It was shown that a technical system state change is fixed at appearance of a deviation of load current distribution comparing with a standard deviation. Analysis of dynamics of a statistical parameter, the standard error (the difference between actual and standard distribution) at a transition process allowed to make a forecast of roller jamming several days before the malfunction took place. The proposed approach of equipment state estimation can become a base for elaboration of a principally new methods of diagnostic of metallurgical rotor equipment.

Multistage Asymmetric Rotors Coaxial Measurement Stacking Method Based on Minimization of Exciting Force

The unbalanced exciting force of high-speed rotary asymmetric rotor equipment is the main factor causing rotor vibration. In order to effectively suppress the vibration of the asymmetric rotor equipment, the paper establishes a multistage asymmetric rotor coaxial measurement stacking method that minimizes the exciting force. By analyzing the propagation process of the centroid of the multistage asymmetric rotor assembly and analyzing the relationship between the geometric center and the centroid of a single asymmetric rotor, a multistage asymmetric unbalanced rotor propagation model based on geometric center stacking is established. The genetic algorithm is used to optimize the unbalance of the multistage asymmetric rotors. Combined with the vibration principle under the exciting force, the vibration amplitude of the left bearing at different rotation speeds under the minimization of the exciting force and the random assembly phase is analyzed. Finally, the experimental asymmetric rotors are dynamically measured, combined with the asymmetric rotors’ geometric error measurement experiment. The experimental results confirm that the vibration amplitude of the assembly phase with the minimum exciting force is smaller than the vibration amplitude under the random assembly phase at three-speed modes, and the optimization rate reached 73.2% at 9000 rpm, which proves the effectiveness of the assembly method in minimizing the exciting force.

A SVDD and K-Means Based Early Warning Method for Dual-Rotor Equipment under Time-Varying Operating Conditions

Under frequently time-varying operating conditions, equipment with dual rotors like gas turbines is influenced by two rotors with different rotating speeds. Alarm methods of fixed threshold are unable to consider the influences of time-varying operating conditions. Hence, those methods are not suitable for monitoring dual-rotor equipment. An early warning method for dual-rotor equipment under time-varying operating conditions is proposed in this paper. The influences of time-varying rotating speeds of dual rotors on alarm thresholds have been considered. Firstly, the operating conditions are divided into several limited intervals according to rotating speeds of dual rotors. Secondly, the train data within each interval is processed by SVDD and the allowable ranges (i.e., the alarm threshold) of the vibration are determined. The alarm threshold of each interval of operating conditions is obtained. The alarm threshold can be expressed as a sphere, whose controlling parameters are the coordinate of the center and the radius. Then, the cluster center of the test data, whose alarm state is to be judged, can be extracted through K-means. Finally, the alarm state can be obtained by comparing the cluster center with the corresponding sphere. Experiments are conducted to validate the proposed method.

VIBRATION ADJUSTMENT OF ROTATING CONVERTERS WITH TECHNOLOGICAL DEFECTS LIMITING THE BALANCING QUALITY

The present-day production and repair of vessels imply saving costs and retaining output quality. One of the cost items is maintenance of processing equipment of manufacturing plants with minimal expense. It can be implemented using up-to-date engineering diagnostics. Suggested tool equipment of vibration diagnostics and vibration adjustment allow not only controlling true technical state of electrical machine, but bring vibration level to target values. The set of methods, including RMS level vibration measuring, narrow-band frequency analysis and spectrum of envelope of vibration, provide insight into complete idea of true technical state of rotor equipment. Vibration adjustment methods, such as alignment, frame flatness setting-out, frame hardening, allow successfully to perform the balancing procedures. The article presents the symptoms of the most widespread defects of rotary converters, which are affected to perform mechanism balancing. Methods of successive elimination of revealed defects are described in detail by the example of converter vibration adjustment. According to the analysis results, application of methods and facilities of vibration diagnostics and vibration adjustment allow to significantly increase repair intervals and, as a consequence, to decrease costs of motor-operated mechanism repair.