Abstract: In order to evaluate stiffness state of the headstock for CNC turning centers accurately, which can provide the modifying suggestions for improvement structural scheme of the headstock, based on thorough investigation of loading theory of full loading device, static stiffness measurement method acted by auto-displacing full load is proposed, in which the static stiffness of the headstock is detected by the self-developed automatic displacement simulate full load loading device. The stiffness and its distribution of turning center’s headstock is analyzed with finite element method (FEM). According to results of the static stiffness measuring experiment and computing fruits with FEM, the structural schema of the headstock is improved by revising the bolt joint between the headstock and the bed, which enhances the static stiffness of the headstock. By comparing FEM analysis with the experimental results of pre- and post structural improvement, the correctness of the measuring method of static stiffness and the effectiveness of improved structural scheme with bolt joint are verified.

Key words: applying simulation with full load;stiffness measurement;improvement of structural scheme;bolt joint