Dynamic Analysis And Structural Optimization Of The High Speed Machine Tool’s Spindle Unit

The high quality of the high speed machine tools is the prerequisite for highspeed machining, and the high speed spindle unit is a key component of the highspeed machining center. In order to avoid the severe deformation or even structuraldamage of the spindle unit resulted from system’s resonance, caused by theconsistency between its natural frequency and the external excitation frequency, theradial stiffness of the spindle’s front and back bearings were calculated, then thespindle finite-element model was built up and the detailed dynamic characteristics inconstrained circumstances were studied. The analyses showed the unit’s naturalfrequencies and mode shapes, as well as the response characteristic around thefirst-order natural frequency region especially for the maximum deformation of suchkey nodes as the spindle’s forepart, central, back-end and the front and back bearingsnodes. The results were helped to find the implementation programs of the spindleunit’s structure optimization and the methods to improve the dynamic performance.The modal parameters of the spindle unit were also extracted from the structuraltesting based on the spindle laboratorial platform. The validity of the FE model wasexamined by comparing the testing results with the finite element analysisconclusions. At the same time, it provided reliable data and design direction for themachine tool spindle’s structural optimization. At last, the parameter model wasestablished for the high speed spindle unit optimization. Selected the designvariables, objective function and constraints, the optimized result was gained byoptimizing control loops. And the static stiffness of the spindle was increased by13.3%after the optimization.