| The high-speed machining technology is one of the c ore technologies in the field of advanced manufacturing,which can greatly improve the machining efficiency,product accuracy and surface quality of parts.High-speed motorized spindle is an indispensable part in the field of high-speed machining.The performance of high-speed motorized spindle under working con dition directly affects the machining accuracy of the product.Due to manufacturing,assembly and other errors,it is possible to lead to the high-speed motorized spindle built-in motor stator and rotor rotation center does not overlap(this paper called static eccentricity),which can cause uneven distribution of the air gap between stator and rotor;In the process of high-speed motorized spindle operation,with the increase of rotational speed,rotor balancing by electromagnetic force is no longer in the radial direction,so the surface of the rotor will generate unbalanced magnetic pull and rotor thermal expansion has intensified at the same time,under the interaction of the two,the high-speed motorized spindle,the rotary center of the built-in motor stator and rotor on the basis of the original static eccentricity,and further intensify the eccentricity(this paper called dynamic eccentricity),the high-speed motorized spindle axis trajectory is beyond the scope of allowed error,ultimately affect the high-speed motorized spindle rotation accuracy.Therefore,in this paper,considering the high-speed motorized spindle rotor is static eccentricity condition,the precondition of further study on the thermal expansion caused by the unbalanced magnetic pull and rotor stator gap between changes on the influence of high speed motorized spindle dynamic characteristics,the different rotating speed of magnetic axis path under the coupled action of hot figure,found that with the increase of rotational speed roto r motion state by single and double periodic motion to chaos to return more than the phenomenon of periodic steady state,and finally by theoretical calculation is verified by the experiments of6000 r/min to 10000 r/min speed axis trajectory within the sp indle rotation accuracy of the conclusion.It has instructive significance in improving its running stability.Specific research contents and problems to be solved are as follows:(1)To build the unbalanced magnetic tension model of high-speed motorized spindle.The electromagnetic field theory involved in high-speed motorized spindle was expounded.Under the condition of constant magnetic field,three calculation methods of electromagnetic force in high speed motorized spindle were discussed.Based on the eccentricity analysis of the internal structure of high-speed motorized spindle,the air gap model between stator and rotor was established.Finally,the unbalance magnetic pull on rotor was deduced by using the Maxwell stress method.(2)Finite element analysis of thermal expansion of high-speed motorized spindle.Finite element method was used to calculate the thermal expansion by the Motor-CAD simulation software,and the conclusion was drawn that the maximum heat concentration in the rotor winding groove of high-speed motorized spindle and the relationship between the rotational speed and the thermal expansion of high-speed motorized spindle was proportional.(3)The analysis of magneto-thermal coupling dynamic characteristics of high-speed motorized spindle.The Newmark-? method was used to calculate the displacement variation of the rotor in x and y directions with time under different conditions with or without gravity coupled by magneto-thermal coupling.(4)Experimental comparison and verification.In different speeds under the test of the high-speed motorized spindle slewing trajectory graph,there is a certain error between the experimental measurement of the slewing radius and the theoretical calculation of the slewing radius,and the theoretical calculation of the slewing trajectory within the spindle slewing accuracy,which verifies the rationality and correctness of the research in this paper. |
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