| The refinement dynamic model of machine electrical spindle is the theoretical basis for ensuring high speed and smooth operation.The structure of electrical spindle is complicated,the principle of statistical energy analysis is used to solve the dynamic model.In this article,the high-speed motorized spindle system is used as the experimental research object,and the whole electric spindle system is divided into two direct coupling subsystems,that the main body of high-speed motorized spindle which is composed of rotor,stator and cylinder is as subsystem 1 and the single structure cylindrical shell end cover is the subsystem 2 of the statistical energy analysis model for measuring coupling loss factor of the double coupling subsystem.The experimental theory is established of the loss factor and the total loss factor,the modal density,the energy ratio of the vibration system and the coupling loss factor.First,under the condition of transient impulse excitation,the vibration response signals of each subsystem is collected and the average internal loss factor parameters in the analysis band of the subsystems are measured by their instantaneous attenuation characteristics.In the process of testing,it is necessary to pay attention to decoupling from its direct connection subsystem so that is acquired from the independent test.Secondly,In the experimental measurement of the modal density of each subsystem,according to the mutual spectrum of the excitation force signal and the corresponding response acceleration signal and the self spectrum of the response to acceleration signal under the transient impulse excitation,the input point admittance of each subsystem is deducted and the actual part is used to calculate the modal density of each subsystem.It is noticed that the direct connection system should be decoupled from its direct connection subsystem;In order to make the test process more concise,to avoid the complexity of the measure of input power.the total loss factor test theory of the coupling system is introduced to indirectly deduce the input power value in the energy balance process of the transientcoupling system.The test measurement about the total loss factor of the coupling system must be coupled with the screw directly.The excitation response signal of the coupling system is obtained by stimulating another of the subsystem and the total loss factor of each subsystem is measured by the transient excitation attenuation method.Finally,the concept of mean admittance is introduced to the process of coupling system coupling loss factor.And the mean value of admittance at the junction point of the direct coupling system is measured.The modal density and the vibration energy ratio of each subsystem in the coupled system are derived by means of the mean admittance method,and the coupling loss factor is derived by the transient energy balance equation of the coupled system.Based on the mean admittance method,the modal density and the vibration energy ratio of each subsystem in the coupled system are derived,and the coupling loss factor is derived by the transient energy balance equation of the coupled system.The experimental measurement method with the transient excitation test theory of the loss factor,the subsystem modal density and the coupling loss factor obtained is used in this article,which is to provide the test method for the non homogeneous,multi-structure subsystem,or the special actual working conditions that enough sensors can not be installed to the vibration coupling subsystem,Through the comparison of the theoretical analysis data,the feasibility of the measuring mode of the coupling loss factor is verified by the transient excitation test.Under the condition of certain accuracy,the test conditions and process are convenient and fast,The dynamic characteristics of the complex coupling system can be predicted quickly,It provides effective data reference for preliminary design and active control of motorized spindle system of high-speed CNC machine tools. |
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