Abstract: To research the pre-tightened loads of the close-combined pre-tightened frame in high-speed precision press, the contact mechanics and the finite element method are employed to explore the non-linear contact problems. For application of the pre-tightened force elements, the precondition conjugate grads solution and Lagrange multiplier algorithm, the finite element analysis models of combined frame are built up to find available pre-tightened value. The increment theory and Lagrange multiplier algorithm about non-linear problem are further discussed. The relationship between pre-tightened load and press deformation are illustrated, and the appropriate pre-tightened loads should be 3.2 MN. The proposed model is validated through the comparison between numerical and experimental results. Under the pre-tightened loads, the dynamic precision of low dead-point can keep within micron-scale and the frame doesn’t offset. The computed and experimental results indicate that the research methods using the contact elements and pre-tightened force elements to compute the contact problem in combined frame can be used to research pre-tightened loads in similar closed combined pre-tightened frame.

Key words: Closed combined frame, Finite element method, High-speed precision press, Pre-tightened force