Research On Dynamic Balancing System Of Micro Rotors

With the gradual development of rotating motors towards high speed,the existence of unbalanced quality of the micro rotor as an essential part of the motor is a key factor affecting the working stability of the motor.The traditional mode of rotor balancing technology can no longer meet the high precision and quality requirements of miniature rotors,and it is becoming more and more urgent to improve the existing balancing technology.Therefore,research needs to be carried out to address the lack of measurement and cutting accuracy of micro-rotors,to complete the improvement of dynamic balancing theory,accurate cutting modelling and the design of the supporting pendulum structure.In this paper,the problem of leveling accuracy of miniature rotors is studied,the influence of the height of the weighting block on the unbalance force of the rotor in the influence coefficient method is considered,the error in the extraction of vibration signals in the influence coefficient method is corrected,the two-sided phase-free dynamic balancing theory is proposed,a high-precision vector model of the cutting area of the rotor is established and the structural design of the support system of the dynamic balancing machine is completed,the main work is as follows:A theoretical correction is made to the derivation process of the double-sided influence coefficient method for micro-rotors,taking into account the influence of the height of the added weights on the unbalance force of the micro-rotor.Based on the use of the same influence coefficient for the same series of rotors,and in combination with the problem of noise in the sensor signal measurement process,multiple sets of measurement data are selected and combined with the Monte Carlo method,and the least squares,complex averaging and amplitude averaging methods are used to analyses the amplitude and phase of the influence coefficient respectively to obtain a more accurate influence coefficient processing method.In view of the limitations of the traditional phase free measurement method in the application to different rotor structures,the general formula of the unbalance measure is derived by graphical analysis of the relationship between the amplitudes in the solution process of the phase free method,and the relationship between the unbalance forces on the left and right sides of the school frontal surfaces of the influence coefficient method is combined to extend the phase free balancing method from single-sided balancing to double-sided balancing.To verify the reliability of the double-sided phase free balancing method,multiple sets of experiments are designed and compared with the traditional influence coefficient method.The experimental results show that the improved method can effectively reduce the unbalance of micro-rotors,and even with unstable phase measurements,the improved phase-free balancing method achieves higher accuracy.For the problem of inaccurate cutting volume in the traditional cutting method,a cutting model based on discrete vectors is proposed.The numerical relationship between the depth of cut and the removal of unbalance is obtained by analyzing the process of cutting a micro-motor rotor with a V-shaped milling cutter.The problem of large errors in the cutting volume due to the complexity of integration and thus simplification of the traditional cutting model is avoided,and the accuracy of the discrete model is verified by comparison with data from simulation experiments.A cutting partitioning method is then proposed to avoid damage to the rotor structure by controlling the number of rotor cuts,in order to address the problem of excessive cutting depths causing damage to the thin-walled rotor structure during the actual cutting process.In order to verify the reliability of the discrete vector model and the cutting splitting method,actual cutting tests were carried out on several sets of rotors,and the test results showed that the remaining unbalance mass on the left and right sides of the rotor was less than 20 mg,and the rotor structure was intact and met the dynamic balancing requirements.To address the influence of the intrinsic frequency of the micro-rotor support system on the testing accuracy of the dynamic balancing machine,a parametric model of the rotor-support system dynamics is established,and the trend of the influence of the system intrinsic frequency and mass on the system sensitivity is obtained through sensitivity analysis of the model.For soft support structures,the system inherent frequency needs to be much lower than the rotor rotational frequency,so the system sensitivity can be increased as much as possible while reducing the inherent frequency.In order to verify the reliability of the inherent frequency calculation model,the modal test results show that the inherent frequency calculation error is between 5% and 10%,which meets the calculation requirements.In order to obtain a reasonable soft support structure,a variable cross-section reed structure is proposed and the reed structure is optimized using a multiobjective optimization algorithm.The test shows that when the system inherent frequency is low,the rotor dynamic balancing measurement accuracy is significantly higher and the stability of the support system is better when using variable cross-section reeds instead of equal cross-section reeds.