The Design Of Virtual Test System For Spindle Rotation Accuracy Decline Of Machining Center

As the key component of the machining center,the accuracy of spindle has a great influence on the accuracy of machining center.And the decline of spindle rotation accuracy during the service period is also an important feature for spindle reliability evaluation.However,the high cost and low efficiency of the physical prototype test greatly hinder the research in this field.Therefore,the increasingly use of virtual test with powerful computer functions has been widely accepted and applied.In view of this,in this dissertation,based on the digital design of the industrial 4.0,a virtual test system for spindle rotation accuracy decline of machining center is designed,taking the spindle of NBP1100 type vertical machining center as the research object.Firstly,in this dissertation,the theory of dimension error model and thermal deformation are studied.Based on the geometric error of the spindle components,the error transfer model is established.Then,through sensitivity analysis,the size factors which have an important impact on the rotation error are found.Also,the affecting factors during the machining process are determined,including mechanical wear and thermal deformation.For the mechanical wear,the relationship between the radial clearance of the bearing and the time is obtained by field wear test.For the thermal deformation,this dissertation mainly focuses on the changes about the gap between the bearing and sleeve under heat.It is established that the main heat source is the friction heat of the bearing and the calculation methods of heat generation of the bearing and heat transfer coefficient are discussed.Finally,combined with the influence of the above two factors,the model of rotation accuracy decline is established.Based on the above research,a virtual reliability test system is constructed in this dissertation with.NET as the development platform and VB as the programming language,making use of its perfect interface design and data transmission function.Combined with the ANSYS parametric command(APDL),the finite element analysis of the spindle system is carried out,and the influence of the thermal deformation on the rotation accuracy is obtained.Then the distribution and decay trend curves of rotation accuracy are obtained considering the combined effects of thermal deformation and mechanical wear,making use of MATLAB relevant calculation models.In the end of this dissertation,the model of NBP1100 vertical machining center and the certain working condition are taken as examples to test the virtual test system.The results show that the system has friendly interface,simple operation and high efficiency.In this dissertation,the virtual test system is designed to provide an effective tool for the evaluation of the accuracy decline during the service period,providing the key technology for the design effect evaluation of digital design.The system can optimize the key parameters during the development of the spindle system and save the test cost,solving the problems on one platform on the one hand and avoiding the loss of data and precision originating from complex data transfer and conversion during the multi-factor synthesis process on the other hand.