Comprehensive compensation method for thermal error of vertical drilling center

To eliminate the influence of thermally induced error from a machine tool on machining accuracy, a comprehensive error compensation method for thermal displacement of the screw shaft and spindle is put forward. Based on a heat transfer mechanism and experimental analysis, a model of screw thermal expansion error is built. Modeling of spindle thermal growth that depends on speed variations is also proposed. Thermal tests for studying thermal behavior of the spindle and screw axis are carried out on the vertical drilling center TC500R. Finally, the compensation effect of the robust model is validated via experimental tests and machining. Experimental results show that thermal displacement variations are controlled within 2 μm when the compensation system is activated. The suggested model can achieve high accuracy and good applicability in different moving states. Machining results indicate that dimensional accuracy of the workpiece is significantly improved after implementation of compensation. Feasibility of the thermal error compensation system is satisfactory in applications for drilling operations.