To investigate the varying dynamical characteristics of CNC machine tool's spindle system at high rotating speed
a thermo-mechanical coupling model of spindle-bearing system is established
which consists of a spindle shaft model and a bearing model. The spindle shaft model is generated by the finite element method considering the effects of centrifugal forces
gyroscopic moments and softening of bearing stiffness. Taking the effects of the radial deformation of bearing inner and outer rings and the change of bearing preload caused by the initial assembly interference between the spindle and bearings
the centrifugal forces and rising temperature into account
the bearing model is improved based on the nonlinear Jones' bearing model. The simulations show that the induced centrifugal expansion of inner ring and thermal expansion of inner and outer rings will strengthen the bearing stiffness while the thermally induced preload lowers the bearing stiffness for the ‘back to back' bearing arrangement. In addition
the centrifugal effect of the spindle impacts the dynamical characteristics more obviously than the softening of bearing stiffness.
关键词
Keywords
references
LIN Chiwei, TU J F, KAMMAN J. An integrated thermo-mechanical-dynamic model to characterize motorized machine tool spindles during very high speed rotation [J]. International Journal of Machine Tools & Manufacture, 2003,43(10):1035-1050.
GAGNOL V, BOUZGARROU B C,RAY P, et al. Modelling approach for a high speed machine tool spindle-bearing system [C]∥Proceedings of the ASME 2005 International Design Engineering Technical Conference and Computers and Information in Engineering Conference. New York,USA: ASME,2005:305-313.
WANG Shuogui, XIA Yuanming.Effect of the interference fit and axial preload in the stiffness of the high speed angular contact ball bearing [J]. Journal of University of Science and Technology of China,2006,36(12): 1314-1320.
RANTATALO M, AIDANPAA J O, GORANSSON B, et al. Milling machine spindle analysis using FEM and non-contact spindle excitation and response measurement [J]. International Journal of Machine Tools Manufacture, 2007, 47(7/8): 1034-1045.
JIANG Shuyun, MAO Hebing. Investigation of variable optimum preload for a machine tool spindle [J]. International Journal of Machine Tools Manufacture, 2010, 50(1): 19-28.
CAO Hongrui, HOLKUP T, ALTINTAS Y. A comparative study on the dynamics of high speed spindles with respect to different preload mechanisms[J].International Journal of Advanced Manufacturing Technology,2011,57(912): 871-883.
WANG Baomin, HU Chibing, WU Zaixin, et a1. Effect of pretension on dynamic stiffness of high-speed angular contact ball bearing [J]. Journal of Lanzhou University of Technology, 2009,35(2): 29-32.
NELSON H D, MCVAUGH J M.The dynamics of rotor-bearing systems using finite elements [J].ASME Journal of Engineering for Industry,1976,98(1):593-600.
NELSON H D. A finite rotating shaft element using Timoshenko beam theory [J]. ASME Journal of Mechanical Design, 1980, 102(4):793-803.