Thermal characteristics testing and thermal error modeling on a worm gear grinding machine considering cutting fluid thermal effect

摘要

The coolant absorbing cutting heat has strong influence on thermal behaviors for high precision machine tool using flood cooling technique. However, the majority of applied thermal error compensation models are without considering cutting fluid thermal effect, which results in poor simulation accuracy of thermal deformation. This paper experimentally investigated the effect of coolant temperature on the thermal characteristics of a worm gear precision grinding machine. Experiments were carried out under three conditions: no-load with coolant, no-load with heated coolant, and load test. Moreover, a real-time thermal error compensation model was theoretically developed and validated based on the experimental data involving the cutting fluid thermal effect. The results show that the temperature distribution of the machine tool was more uniform and the temperature gradient was decreased when the grinding heat was partially considered using heated coolant, which indicates that coolant can positively affect the thermal behavior if it is controlled to flow correctly. The thermal error compensation model was built based on the optimal four temperature variables and with a high accurate prediction and robustness. For the no-load operating conditions, the maximum absolute errors and mean absolute errors are 2.7 mu m and 1.5 mu m respectively. For the load operating conditions, the prediction accuracy of the model built by no-load measuring data is also greatly improved because the grinding heat is partially considered by heated coolant in the no-load test. And the maximum prediction error is 13.0% when the influence of the feed drive system adjustment is considered.