Measurement and modeling of thermal errors in dual-drive servo feed system

To investigate the effect of thermal characteristics of dual-drive feed system on CNC machine tool precision, a laser interferometer, an infrared thermography and a temperature displacement acquisition system are adopted to measure the distribution of temperature field and the thermal deformation at different feed rates for a high-precision CNC boring machine. The nonlinear relationships of thermal error with screw temperature, location coordinates and thermal equilibrium period are analyzed, and a comprehensive thermal error model is then proposed. It is found that an uneven distribution of temperature field gradient due to synchronous dual-drive structure leads to thermal deformation, the relationships of thermal error with screw temperature and location get as exponential and linear respectively. The farther the measured point is away from the motor, the lower the positioning precision is. Moreover, the thermal error and equilibrium period increase with the feed speed. The model prediction accuracy can reach 85% with perfect generality under different cutting conditions.