Estimation of volumetric accuracy based on linear error motion in machining centers

Abstract

ISO230-1, an international standard of test code for machine tools, has been revised for the first time in 16 years. A volumetric accuracy for three linear axes was defined as a term of multi-axes motion in the revision of ISO 230-1. As a matter of course, the volumetric accuracy is closely connected with the linear axis error motions in three axis machining centers. The error motions of linear axes have been checked in compliance with ISO 10791-1 and -4 for a long time. However, the relationship between the measured error motions of linear axis and volumetric accuracy has not become clear. In this paper, the positional deviations of lattice points within the entire working volume of machining centers were measured via laser interferometer. Positional deviations were estimated by using a mathematical model in consideration of measurement coordinate systems and the tested linear error motions. As the results, the estimated positional deviations of the volumetric accuracy corresponded reasonably well with the measured deviations in a small machining center.

Keywords

• volumetric accuracy
• positioning deviation
• angulaer deviation
• linear axis
• error motion
• machining center
• laser interferometer