Graphical presentation of error motions of rotary axes on a five-axis machine tool by static R-test with separating the influence of squareness errors of linear axes

This paper presents an efficient and automated scheme to observe error motions of rotary axes on a five-axis machine tool by using the R-test. During a five-axis measurement cycle, the R-test sensors nest measures the three-dimensional displacement of a sphere attached to the spindle in the coordinate system attached on the rotary table. This paper first demonstrates an intuitive, graphical presentation method of R-test measurements to understand how error motions of rotary table change in three-dimensional space depending on the swiveling angle. A critical issue with the error calibration by the R-test is that error motions of linear axes must be sufficiently small as a prerequisite to calibrate component errors of rotary axes. To partially address this issue, this paper proposes a scheme to separate squareness errors of linear axes by performing a set of R-test measurement cycles with different sphere positions.

► R-test measures the 3D displacement of tool center position on five-axis machine tools. ► This paper demonstrates intuitive, graphical presentation of R-test measurements. ► It clarifies how error motions of rotary table changes with the rotation of swiveling axis. ► Error motions of rotary axes are numerically parameterized. ► We propose a scheme to separate squareness errors of linear axes from R-test results.