The problem of impact during the mold opening and closing was analyzed due to the low expansion ratio under 25 000 kN clamping force

and optimization design on the hinge system was carried out. Firstly the mechanical model of the clamping mechanism was built up and the stress and displacement were calculated using finite element method in order to validate the stiffness and strength of each component. A rigid-flexible combination multi-body dynamic model of the hinge system was set based on the parameter of elbow stiffness. Finally the optimized design was built up upon the multi-body dynamic model using elbow hinge coordinates as design variables. As the results of comparison with the origins

the optimized design has enlarged the expansion ratio from 21.45 to 24.57

and the stroke is increased from 1.03 to 1.08. The impact during mold opening and closing of the optimized design is decreased greatly.