In order to solve the problem of accurate forming of asymmetric cross-section truss strip of skin frame of C919 domestic large aircraft

the constitutive model and springback law of materials were obtained based on the performance test and evaluation of 2099–T3 and T83 Al–Li alloys with 2–shaped profile and L–shaped profile. At the same time

a new piecewise constant curvature progressive roll bending process is proposed. Combined with the theoretical analysis and calculation of roll bending forming

the finite element model of constant curvature four-axis roll bending is  established

and the influence factors of roll bending springback and curvature radius of two types of profiles are analyzed. The simulation results determine the reasonable roll bending process parameters of asymmetric cross-section profiles as follows: the friction coefficient between profile and roller is 0.10–0.12

the clearance between profile and roller is 0.2 mm

and the limit lifting heights of left and right rollers of 2–shaped profile and L–shaped profile are 43 mm and 30 mm

respectively. Finally

the qualified variable curvature profile parts were successfully produced by the MC4P431IAS CNC roll bending machine using the method of piecewise equal curvature asymptotic roll bending

and the roll bending process test verification of variable curvature profile was completed. The maximum clearance value is only 0.76 mm

which successfully verifies the feasibility and accuracy of the variable curvature rolling forming scheme. At present

the research results have been successfully applied to the roll bending production of fuselage skin skeleton truss in large aircraft of C919.