A rapid identification method for angular positioning error of rotary axes for machine tools with 5 axes based on a double ball-bar

Rotary axes are key parts of machine tools with 5 axes and their geometric errors affect the accuracy of the machine. The angular positioning error is the most important error source of rotary axes. An identification method for angular positioning error of rotary axes of machine tools with 5 axes based on a double ball-bar (DBB) was proposed. Through tangential installation of the DBB and combining this with the synchronous circular motion of linear axes, the angular positioning error model including errors of linear axes and other 5 errors of rotary axes was established. To eliminate influence of geometric error reduced by linear axes of the machine, the influence model of linear axes geometric error of machine tools with 5 axes on the length of the DBB was established and the linear axis geometric error was measured by laser interferometer. Measurements for angular positioning error by both DBB and laser interferometer were conducted, and results indicate that the maximum error between them is 0.0018°, which is no greater than 2.59%. The proposed method does not need expensive measuring instruments, and is rapid and efficient.