Abstract: With the improvement of machine tool accuracy, clear and effective machine tool calibration methods and solutions have increasingly become a problem that plagues the R&D, production and application industries of high-precision machine tools. This paper starts from the three main technical elements of machine tool calibration - modelling theory, measurement methods, and compensation strategies for machine tool machining errors. Based on the construction of the equivalent kinematic error function of machine tools, a complete set of high-precision machine tool accuracy calibration methods including test pieces design, machining measurement methods, and machine tool load compensation strategies is proposed and applied to actual high-precision machine tool calibration. Firstly, based on the theory of multi-body systems, a motion error model for the complete motion chain from the tool to the workpiece on the machine tool is established. the mathematical mapping relationship between the motion errors of the machine tool and the geometric errors of the workpiece being machined is clearly define. Furthermore, the motion relationship of the machine tool is analysed, and the 9 equivalent motion error functions are determined to characterize the 21 motion errors of the three-axis machine tool. Thirdly, the decoupling of equivalent motion errors and the analysis and prediction of the errors under loaded conditions are realized through the design, manufacturing, and measurement of test pieces. Finally, the data of equivalent motion errors under loaded conditions are incorporated into the machine tool processing program. Typical specimens are processed and measured, resulting in a significant reduction of errors in concentricity, perpendicularity, parallelism, tilt, and others about 12.31%～74.47%. The high-precision machine tool accuracy calibration method, based on equivalent kinematic errors and not requiring the identification of machine tool error sources, predicts and compensates for the geometric errors of the processed workpiece. This enables the characterization, validation, maintenance, and improvement of machine tool accuracy performance. The study presented in this paper offers a straightforward and effective loaded accuracy calibration method for machine tool manufacturers and end-users.

Key words: machine tool calibration, equivalent kinematic errors, on load machining accuracy, test piece, error prediction and compensation