Influence of friction on initial setting position of preform for final forging process of large-scale titanium alloy strut

The friction and initial setting position of preform have an important influence on the metal flow and cavity filling during die forging process of large-scale component, especially for closed-die forging with flash of large-scale titanium alloy strut. This paper studies the influence of processing parameters on the die forging process of large-scale strut by targeting the filling difference (f) between right and left cavities, and some relational models such as relationship between friction and preform position were established. The results indicated that the friction amplitude (m) and initial setting position (x) of preform have notable influence on the filling states of right and left cavities, but the loading speed (v) of upper die and initial temperature (T) of dies have little influence on the filling state; with the initial position of preform moving to right cavity (head of strut), the fluence of m on f reduces, but the fluence of x increases; the established relationship between m and x can obtain the feasible region with an optimal point for initial setting position of preform, and the feasible region with a linear range for the initial setting position of preform can be obtained by considering the expected accuracy of filling difference f, and then the feasible region with an areal range for the initial setting position of preform can be obtained by considering the fluctuation of frictional condition in further.