Development of a Robust and Real-Time Thermal Deformation Prediction System for Machine Tool by Multi-Point Temperature Measurement

More than 70% of machining errors in machine tools are caused by thermal displacement. In this paper, we proposed a method of estimating for thermal displacement by measuring the temperature at a large number of points to achieve high-precision machining under disturbances such as cutting fluid. The sensor locations were determined from the results of the thermal simulation in which the heat generation at various heat sources, such as bearings and ball screws, were determined according to the results of the operational tests. The tool center point (TCP) error was estimated from the temperature distribution measured by 284 temperature sensors. The proposed method reduced the estimation error by 50% compared to the conventional method with 17 temperature measuring locations, and the accuracy was confirmed to be unchanged even when cutting fluid was supplied. In addition, a real-time method to estimate TCP relative displacement was developed to implement thermal deformation compensation in a machine tool. Considering actual machining, it is necessary to reduce the computational load of the finite element method (FEM) or to consider a faster displacement estimation model to output the TCP relative displacements at multiple points. By implementing this thermal displacement estimation system, it may be possible to achieve high-precision machining even with machines that do not have high precision.