Research On Deterioration And Sustainability Evaluation Of Rotation Accuracy Of Motorized Spindle

As the core functional part of CNC machine tools,the rotation accuracy and sustainability of motorized spindles directly affect the machining accuracy,machining efficiency and machining stability of CNC machine tools.At present,there is still a large gap in the level of accuracy sustainability between domestic and imported motorized spindles.Studying on the degradation of rotation accuracy of motorized spindle,mastering the degradation mechanism and degradation law of the rotation accuracy of motorized spindles have important value for predicting the machining status of CNC machine tools,which is the basis and key to improving their accuracy sustainabilityThe research carried out in this paper originates from the national major scientific and technological special topic--"Research on the Common Technology Research and Capacity Building of Functional Components Testing and Testing",which takes the motorized spindle of the machining center as the research object,uses a combination of theoretical and experimental research to conduct research on the degradation mechanism and degradation law of the motorized spindle rotation accuracy,establishes the deterioration model of rotation accuracy and explores the rotation accuracy sustainability level of motorized spindle.The main research contents of the paper are as follows1.Research on influencing factors and degradation of motorized spindle rotation accuracy.By studying the structural composition of the motorized spindle system and the formation mechanism of the rotation error,it is determined that the key parts that cause the rotation accuracy degradation of the motorized spindle are the support bearing,the shaft,the joint surface of the spindle and the tool handle.It is also concluded that the main factors affecting the rotation accuracy of the motorized spindle are the bearing clearance and the thermal deformation of the system,the rotation accuracy degradation of the motorized spindle starts from the wear and degradation of the core supporting component bearings.The increasing bearing clearance further increases the radial runout of the motorized spindle,and the rotation accuracy of the motorized spindle degenerates2.Establish a degradation model for the rotation accuracy of the motorized spindle From the perspective of bearing wear,the theoretical research on the rotation accuracy degradation of the motorized spindle is performed.Based on the Hertz contact theory,the contact analysis of angular contact ball bearings is carried out,and the calculation methods of contact stress,load displacement coefficient,and load distribution are obtained.The wear analysis of the contact ball bearing is carried out to obtain the calculation methods of the number of contact cycles,slip speed and wear depth.Based on the relationship between the bearing clearance and the radial runout of the motorized spindle,a rotation accuracy degradation model of the motorized spindle is established3.Experimental research on the rotation accuracy degradation of the motorized spindle.The experiment scheme for the rotation accuracy degradation of the motorized spindle,the detection scheme for the rotation error,and the evaluation scheme for the rotation accuracy were formulated.Experimental research on the rotation accuracy degradation of a domestic 150-type motorized spindle for machining center is conducted.Through the load simulation of the real working conditions,the rotation accuracy degradation of the motorized spindle in 300h is 1.87?m,and based on the load condition coefficient the calculation result of the rotation accuracy degradation model of the motorized spindle is 1.7?m,which verifies the rotation accuracy degradation model of the motorized spindle4.Research on the rotation accuracy sustainability of the motorized spindle.The accuracy sustainability level was evaluated combining with the calculation example of rotation accuracy degradation model of a domestic 150-type motorized spindle for machining center,and the accuracy sustainability level of the motorized spindle was measured based on the effective accuracy sustainability time.Select the allowable accuracy level 15?m,and the effective accuracy retention time under the specified conditions n=1000r/min and P=1000N is te?3.889×105 min=6482h.