Process parameters and limits in tube hydro-forming with axial feeding

By using the viscous media, tube hydro forming with axial feeding was investigated. Based on the diffusion instability and plasticity theory, the distribution rules of the internal pressure were indicated and the relationship between the internal pressure and the axial loading were obtained with axial symmetrical part. After creating the loading function to control the loads, the method to control the axial feeding was proposed and the loading mode was optimized. Based on the localized instability theory, the limits of the internal pressure were calculated, and the UDL (uniform deformation limitation) and the concept of LSR (limited stress ratio) were proposed to check the basic workability of parts. After analyzing the features of stress variation during forming, the mechanism that the stress state changes quickly from the tension-compression to the dual-tension was carried out. Through the experiment and numerical simulation, the forming process of the tube hydro forming with axial feeding was conducted and it proves that the results from the theoretical analysis keep a reasonable agreement with the reality.