Abstract: To improve the comprehensive performance of CNC machine tools, a steel-concrete composite structure bed is designed, based on a certain horizontal machining center cast iron bed. The method of orthogonal experiment, grey theory and combination weighting is used to optimize its structure, the optimal parameter combination is obtained. Finally, the finite element simulation analysis of the composite structure bed is carried out, and the results are compared with the prototype cast iron bed. The results show that: when the bed mass is increased by 2.3%, the maximum static stress and the maximum static deformation of the composite structure bed are reduced by 51.3% and 82.9%, respectively. The first three natural frequencies are increased by 143.9%, 156.8% and 148.7%, respectively. The maximum amplitudes of the center nodes of x-axis guide rail and z-axis guide rail in x, y and z directions are decreased by 97.6%, 97.1%, 94.0% and 99.6%, 97.9% 85.4%. When the sliding block of the guide rail continuously rubs on the guide rail surface for 1 800 second, the maximum thermal-structural coupling deformation of the guide rail is reduced by 7.3%.

Key words: composite structure bet, orthogonal experiment, grey relational analysis, combination weighting, multi-objective optimization