On-machine measurement of thermal influence of the long-span crossbeam of gantry machine tools using a 3D laser profiler
Zhiyang Zhao, Nuodi Huang, Lei Zhong, Zhengchun Du, Soichi Ibaraki, Limin Zhu
Abstract
For gantry machine tools, the large-span beam is an important structural component, and its deformation is
significantly affected by temperature. It is still a crucial problem to identify the thermal error of the motion axis
continuously and in real-time. This paper proposed an on-machine measurement (OMM) method to evaluate the
thermal influence on long-span crossbeam of the gantry machine tools, using a high-precision 3D laser profiler
and a set of artifacts. Firstly, kinematic model to compute the deformation of the crossbeam is established
considering the position calibration of the laser profiler. As the Y-axis relies on the crossbeam, thermal errors of
the Y-axis are identified to evaluate the thermal influence on long-span crossbeam. Secondly, algorithms for the
position calibration and the point cloud registration are proposed to solve the calibration matrix and the relative
transformation matrix of the 3D laser profiler in the kinematic model. The thermal error of the Y-axis can then be
identified by utilizing the developed kinematic model. Finally, a continuous warm-up experiment was carried out
on a three-axis gantry machine tool, and the six thermal errors of the Y-axes during the warm-up process were
calculated. The results verify the effectiveness of the proposed method. In addition, uncertainty analysis is
conducted to evaluate the effect of the 3D laser profiler calibration error on thermal error identification based on
the experimental results. It is proved that the proposed thermal error identification method is insensitive to
position calibration errors.
Keywords: Thermal error, Long-span crossbeam, On-machine measurement, Gantry machine tool, 3D laser profiler
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