Design And Research On Spindle Assembly Of High-speed Vertical Machining Center

High Speed Machining, as an important branch of advanced manufacturingtechnology, improves the processing efficiency, accuracy and quality of theworkpiece, through a substantial increase in cutting speed and has become anirresistible trend of the development. The high-speed machine is the primarycondition for achieving high-speed cutting. High-speed vertical machining center,a representative of high-speed machine tools, has been included in the nationalmajor scientific and technological project "high-end CNC machine tools andbasic manufacturing equipment". High-speed spindle is a core component ofhigh-speed vertical machining center, and has a critical influence on the overallperformance of high-speed vertical machining center. So that, it has an importantsignificance to do design and research of high-speed spindle and break itsdifficult technical problems.This paper first briefly introduces the basic principle of high-speed spindleand structural design of high-speed spindle is done, whose three-dimensionalmodel spindle are built up with Solidworks; Then, by applying Lumped MassParameter Model and Transfer Matrix Method, its dynamic model is established;Finally, by the simulation software and experiments, to further analyze andresearch the dynamic and thermal properties of high-speed spindle. Specificinclude:（1）The detailed design and calculation of high-speed spindle mandrel isdone. After the completion of selection of built-in motor and high-speed bearings,both cooling system and lubrication system of high-speed spindle are designedand some key design problems are solved.（2）Through the use of Solidworks software, three-dimensional model ofhigh-speed spindle assembly is established, providing an intuitive solid modelfor further research on spindle performance. （3）The high-speed spindle dynamics model is established by applyingLumped Mass Parameter Model and Transfer Matrix Method. Then, the naturalfrequencies and mode shapes of high-speed spindle are calculated and solved byprogramming computing, and thus vibration characteristic of high-speed spindleis analyzed by using mathematical methods.（4）Modal analysis is done for simplified spindle model in Solidworksplug-in COSMOSWorks, and dynamic performance of high speed spindle isstudied further. The natural frequency of each vibration mode is obtained. Incomparation with analysis results obtained through Transfer Matrix Method, thecauses of the differences are found out. The results show that the maximumspindle speed of designed high-speed spindle is much smaller than the firstcritical speed, the resonance of spindle can been effectively avoided, and it canmeet design requirements.（5）The heat source and heat transfer mechanism are analyzed and heatgeneration of the heat built-in motor and high-speed bearings under spindlesteady-state operation are calculated. Then Three-dimensional FEA model isbuilt up with ANSYS. By applying boundary conditions and load, thesteady-state temperature field of high-speed spindle is obtained. Based on theabove-mentioned analysis, some measures are put forward to improve thethermal characteristics of high-speed spindle.（6）At last, the dynamic performance and thermal performance experimentsare done by DHDAS dynamic signal measurement and analysis system.