Simulation of the machining error of variable-axis NC machine tool based on static stiffness

The machining error of a variable-axis NC machine tool is analyzed by studying the deformation of Stewart platform, the kinetic part of the machine tool. Vector expression of machining error is derived on the condition of static loads. Moreover, the machining error is preadjusted by establishing a relevant pre-adjusted model. The method is universal and provides a theoretical foundation to improve the machining accuracy of the machine tool in static stiffness. A simulation example is finally given, demonstrating that the machining error arisen from the static stiffness does exist and the error has to be corrected.