A method for tracing key geometric errors of vertical machining center based on global sensitivity analysis

This paper proposes a method for tracing key geometric errors of vertical machining centers based on global sensitivity analysis in order to address inconsistent dimensions associated with sensitivity coefficients, random analytical variables, and geometric errors across different positions. The kinematic chain forward solution and the volumetric error model of vertical machining centers based on a global coordinate system is constructed by means of screw theory; the identification model is constructed based on the double bar ball measurement principle. The identification model is transformed into an optimization-design problem, which is solved by a simulated annealing–genetic algorithm. The idea of orthogonal experimental design is used for reference, and 25 test points are selected for the machine tool workspace. By taking the volumetric error model as a sensitivity calculation model, and by taking geometric errors as analytical factors, multi-factor orthogonal experiments and single-factor parametric tests are designed, respectively. The F-values of the significance test results of the orthogonal experiments and the Euclidean norms, ∆P and ∆O, of the parametric test results are used as global sensitivity coefficients. The analysis results suggest that the traceability results of the key geometric errors are essentially the same across the two tests and the 13 key geometric errors of the J₁VMC400B vertical machining center are traced.