Numerical Simulation Of Stretch-Bending Process For Rocket Frame Ring

In this paper,the stretch-bending process of rocket frame ring is mainly studied.The stretch-bending process of profiles with arbitrary cross-section is analyzed by analytical method.The stretch-bending process of profiles with ?-shaped symmetrical section and asymmetrical L-shaped is studied by numerical simulation method respectively.The main technological parameters and die geometry are obtained,which provides a reference for engineering production.The main contents of the study are as follows:The stress and strain distribution of profiles with arbitrary cross-section in stretchbending process is analyzed by analytic method.The mechanical models of stretchbending with tensile force less than yield strength and with tensile force greater than yield strength are established,and the expressions of stress,strain and neutral layer of profiles after tension-bending are obtained.The mechanical model of reverse loading during springback is established,and the strain distributions of profiles after unloading and springback are analyzed.The expression of curvature radius after rebound is obtained.Aiming at the stretch-bending process of ?-shaped symmetrical section profile,the influences of the stretch-bending process parameters such as the vertical height,pretension,replenishing amount and friction coefficient on the forming quality were analyzed.The results show that proper reduction of the vertical edge height and tensile amount can effectively reduce the distortion of the section;and the springback can be reduced by increasing the pre-stretching amount and the replenishing amount and reducing the friction force.According to the simulation results,the appropriate process parameters were determined,and the radius of the die was obtained by compensating method.Aiming at the stretch-bending process of L-shaped asymmetric section profile,the lateral bending problem of asymmetrical profiles after unloading was analyzed,and the influence of stretch-bending process parameters on forming quality was analyzed.The research shows that reducing the vertical edge height properly can reduce the cross section distortion,increasing the baffle clearance properly is beneficial to the clamping,and has little effect on the cross section distortion;increasing the tension and reducing the friction force are beneficial to the reduction of the lateral bending;according to the influence of the pre-stretching amount,the replenishing amount and friction coefficient on the springback,the appropriate process parameters were determined,and the radius of the die was obtained by compensating method.