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To improve the stretch-bend forming precision of aluminum alloy profiles with complex open sections, the relationship stressestrain distribution and the spring-back radius variation were analyzed under different stretch-bend stages. Numerical simulation was performed on the auxiliary mold stretch-bend and spring-back process for the L-section aluminum alloy profile with variable curvature. The effects of cover plate pressure and baffle gap on residual stress, section deformation and spring-back value after forming were investigated. The results show that the stretch-bend warpage can be avoided by setting the cover plate on the straight section of the profile web plate. With the increase of the cover plate pressure, the section distortion of the vertical plate increases by 82%, and the maximum spring-back increases by 71%. A baffle plate was added to the outside of the vertical plate, and the baffle gap is proportional to the amount of section distortion and inversely proportional to the spring-back value. The critical cover force (1 kN) and the critical baffle gap (1 mm) obtained by numerical analysis are used in the stretch-bend forming experiment, and the maximum error between the two results is 2.39%. The numerical simulation has a certain reference value for the rational design of the auxiliary mold stretch-bend process parameters. [ABSTRACT FROM AUTHOR]

Low-frequency vibration assisted bend-stretch forming has a good friction reduction effect due to the “surface effect” and enhances the forming ability of materials compared to traditional bend-stretch forming. In order to further improve the friction state of the forming contact interface, the contact interface friction between AL6005A aluminum alloy and Q345B steel under low-frequency vibration was analyzed by using the elastic-plastic contact theory. The formula for calculating the sliding friction coefficient of contact pressure and low-frequency vibration parameters was established. The influence of forming contact pressure and vibration frequency on the contact stress, friction force, and friction coefficient of asperity at the contact interface is obtained through the simulation analysis of low-frequency vibration sliding friction of double rough contact surface. The results show that the application of lowfrequency vibration can weaken the influence of contact pressure on the friction coefficient and reduce the friction coefficient between AL6005A aluminum alloy and Q345B steel. Within a specific range of contact force, the sliding friction coefficient decreases first and then increases with the increase of vibration frequency. There is a critical vibration frequency to minimize the sliding friction coefficient of the contact interface. [ABSTRACT FROM AUTHOR]