Mechnical Design Systems Laboratory, Hiroshima University

Conventional thermal deformation tests, described in e.g. ISO 230-3:2007, only measure the displacement of the tool center point when it is positioned at a single point (or two points at most). However, the heat often affects the volumetric accuracy over the entire workspace. In our previous work, a new scheme was proposed to identify the thermal influence on two-dimensional motion trajectory by single-setup tracking interferometer measurement. This paper first clarifies that this scheme can be subject to significant measurement error when the entire trajectory is linearly translated due to simple thermal expansion. Then, this paper proposes an improved scheme to avoid it by direct measurement of translational movement by using displacement sensors. The experiment result and the uncertainty analysis are also presented.

Keywords: Measurement, Machine tool, Thermal error