Studies On Key Technologies In Hard Bearing Dynamic Unbalance Measurement

Considering the high efficacy and general feature, hard-bearingbalancing machine has advantages over soft-bearing one in unbalancingmeasurement. These advantages are from its vibration responseequivalent to static force when ignoring the rotor’s inertia. In the presentresearch, vibration response is analyzed by the establishment of dynamicdifferential equation. To obtain distinct physical-mathematical equation,these analyses do not involve the influence of the base. In the thesis, themulti-body dynamic model, comprising the mass and rigidity of the base,is introduced to comprehensively analyze vibration response ofunbalancing machine. Besides lower computational complexity, thismethod can get more vibration information of unbalancing machine andprovide theoretical evidences for designing the base of the balancingmachine。The extraction efficacy and precision of unbalancing signal is limitedby the length of the sampling data. MUSIC spectrum based on residualerror, which can predict the element and structure of the unknown signal,is presented to improve this problem. The amplitude and phase of theunbalancing signal can be determined after matching signal retrieval. Theexperiment results validate this proposed method could improve theextraction precision of unbalancing signal from the limited lengthsampling signal.To further improve extraction precision of unbalancing signal fromshorter data, AR model is adopted to predict and extend the shorter signal,with the result of expanding useful information of the specimen. Then the above MUSIC spectrum is used to separate unbalancing signal from thepredicted signal. The final experiment results show the effectiveness ofthis method in terms of shorter sampling data.There are various processing methods to extract unbalancing signal,but lacking of a criterion to evaluate their effectiveness. Especially, thereis short evaluation method of performance of the measurement system ofbalancing machine. A new method is proposed to simulate the vibrationsignal of the balancing machine. Based on analyzing the disturbancesources, the AR power model of vibration signal is built, and the principleof AR order is proposed. Then the improved covariance method isapplied to estimate the parameters of power model. Vibration signal canbe obtained after the built Gauss white noise goes through this AR powermodel. Experiments results show the effectiveness of this simulatedvibration signal.Finally, a hard-bearing balancing prototype machine is realized. Thisdesigned unbalancing machine has excellent properties, includinguser-friendly interface, robust stability, great extensibility and highmeasurement precision with0.1μm minimum achievable residual and95%unbalance reduction ratio.