Abstract: In order to study the thermal deformation law and to realize the real-time compensation for CNC machine tools, the theoretical and experimental analysis for CNC machine tool spindle thermal deformation are carried out. Results show that the relationship between the spindle thermal deformation and the spindle temperature is approximate linear relationship at about 1/3 distance away from the heat sources. That is to say, the spindle thermal deformation exist pseudo-lag. This conclusion provides a theoretical basis for temperature sensor setup and thermal error robust modeling. To verify the thermal deformation pseudo-lag, the spindle thermal errors of a VM850 machining center is measured, and the thermal error model is established according to the least square method. The spindle thermal deformation is compensated using the real-time error compensation system. The spindle thermal error is reduced by 90% compared with no compensation, and the spindle accuracy is greatly improved.

Key words: CNC machine tool, Error compensation, Pseudo-lag, Thermal deformation