An improved geometric error analysis method considering the variety of sensitivities over working space

Abstract

Machine tool accuracy analysis has become increasingly important since accuracy as the major parameter of a machine is to a large extent determined by geometric accuracy design. In order to improve the comprehensiveness and veracity of geometric accuracy design, this article proposes an improved geometric error analysis method considering the variety of sensitivities over working space. A multi-rigid-body model which includes cutting tool’s wear-out error and workpiece’s clamping error is established to represent the position relationship of machine tool’s working components. The expression of geometric error is converted from matrix form to screw form through the screw mapping theory, so that rotational error can be expressed and calculated directly like the translational error. Considering motion errors along axes over the whole working space instead of at a fixed position, an improved sensitivity analysis algorithm is conducted to identify, among 38 components of errors increased the variety with tool wear and clamping errors, which of them have a significant impact on four different types of machine errors. Finally, the proposed method was implemented and validated on a horizontal boring machine, and the sensitivity analysis results over working space would offer vital evidence for the machine’s geometric accuracy design.