Construction of a simple model for compensating real-time thermal deformation in machine tools

Thermal deformation in machine tools causes relative displacement between the spindle and the turret, leading to a decrease in machining accuracy. Methods using detailed finite element models and simple prediction equations have been proposed. However, the huge amount of calculation and the reduction of the correction effect outside the test range have been a problem. Therefore, in this study, we targeted a commercially available CNC lathe and proposed a method for constructing a model that achieves both low calculation speed and high prediction accuracy of thermal deformation by representing the parts that contribute to relative displacement with a low-dimensional FEM model. By simplifying the spindle and the turret into a rigid-body model using this process, the displacement agreed with those of the FEM model in some areas. Furthermore, using a model that simulates a bed, we reduced the number of nodes while maintaining displacement accuracy by applying shell elements to areas contributing to the spindle and the turret displacement, and rigid-body models to areas that do not.