| Multi-axis machine tools are important units in modern production systems. The complex structures of the machine tools produce an inaccuracy at the tool tip that influence the quality of machined parts, the propagation of kinematics errors forming the principal volumetric error source in the workspace. To improve the accuracy of machine tool, kinematic errors must be defined and modeled mathematically.; Many studies use the polynomials to represent kinematics errors of machine tools. However, in practice the representation capability of these polynomials was not verified in a rigorous way.; In this work, kinematics errors of five-axis machine tools were measured experimentally, and a polynomial model was used to represent theses errors.; In the literature, backlash is recognized as one of the kinematics errors, then its integration in the model is capital. Since the backlash occurs when the direction of approach is reversed, all measurements were carried out bidirectionally. Repeatability, exactitude and reproducibility of these results are also presented.; A strategy based on statistical tests was developed to choose the degree of the most representative polynomial for each error with minimum coefficients.; Many researchers studied the behavior of backlash, but nobody evaluated experimentally and statistically its contribution. In this work, the integration of backlash in the model is statistically represented with an indicator variable. A statistical test was also applied to test the marginal contribution of backlash.; In order to generalize our model and see its behavior with other machines, test were applied on three types of machine tool using a varied guidance technology like roller slide or hydraulic pad.; Based on the resolution and the repeatability of the machines, the residue analysis method accompanied with polynomials smoothing technique proved the good quality of adjustment for the majority of kinematics errors of the various machines tools. |
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