The technical method of geometric error measurement for multi-axis NC machine tool by laser tracker

Abstract

The machining accuracy is an important index to evaluate the machine tool characteristics, and error measurement and compensation are effective methods to improve the machining accuracy with low cost. Error measurement is a prerequisite and basis for error compensation, so how to quickly and accurately measure the machine error is particularly important. To quickly and accurately detect the geometric error of multi-axis NC machine tool, a new method with laser tracker based on the sequential multi-lateration measurement principle is proposed in the paper. The laser tracker is used to measure the same motion trajectory of the linear axis and rotary axis of machine tool at different base stations. Based on the GPS principle, the space coordinates of each measuring point can be determined by large amount of measured data. Then according to the error model of the linear axis and rotary axis, each error can be separated. In the paper, the principles of sequential multi-lateration measurement are analyzed in depth. By establishing the mathematical model of sequential multi-lateration measurement for the linear axis and rotary axis, the algorithms for linear axis measurement and rotary axis measurement are derived and proved feasible by simulations, respectively. Meanwhile, the error separation algorithm is also deduced. The results of experiments show that this method can achieve quick and accurate detection of errors in multi-axis NC machine tool.

Geometric Error Measurement and Identification for Rotational Axes of a Five-Axis CNC Machine Tool

“…In addition to the aforementioned methods, it is feasible to apply a laser to error measurement in rotational axes [23] and [24]. Wang et al [25] and [26] proposed a method to measure the geometric errors of rotational axes by way of a laser tracker. Based on a sequential multi-lateral measurement principle, the motion trajectories of rotational axes and the space coordinates of each measuring point were measured at different base stations.…”

Reproducibility of machine tools’ circularity test according to ISO 230-4 with respect to testing position

“…We can mention at least laser track test, ball bar test, R test [1][2][3][4][5][6]. Laser tracer test is commonly used for generating the whole vector space of Volumetric Error (VE) [7]. Since the test is time consuming, which translates in to higher costs, it is not recommended to use it in standard technical inspector.…”

Optimization Method for Solution Model of Laser Tracker Multilateration Measurement

“…Zhang et al from the engineering college of Durham University made further study of optimization of multilateration set-ups and measurement plans [6]. Wang Jindong applied the multi-station and time-sharing measurement to machine tool correction [7]- [9].…”