Facing the machining accuracies

a methodology of identifications and tolerance design of machine tools crucial geometric error elements (CGEE) is proposed. Taking a vertical machining center as the object

the volumetric error of machine tools is modeled based on screw theory. Combined with the volumetric error model and the definitions of machining accuracies

the machining accuracies evaluation models are established

and the indirect experimental verification strategies and implementation technologies are proposed. The CGEE can be identified by orthogonal experiment and statistical analysis

and the identification results are verified by numerical experiment. Then

the mapping relationship between machining accuracies and CGEE is constructed based on response surface method

and the tolerance design of the latter is transformed into an optimization problem. Genetic algorithm is used to obtain the optimal tolerance of CGEE. While the machining accuracies meet the requirements

the product cost of machine tool is the lowest

which shows that the proposed method is conducive to the robust design of machine tools accuracies.