Analysis of Multistage Tube Profiling

Multistage tube profiling, characterized by sequential deformation across multiple passes, offers significant advantages in metal forming, particularly for producing complex geometries such as star-shaped profiles with deep corrugations. This study investigates the deformation behavior and material plasticity during multistage profiling, focusing on processes like multistage drawing through dies or rolling on multistand mills. The research highlights two analytical approaches: one assuming uniform plasticity and another accounting for nonuniform plasticity, especially relevant for materials with significant strain hardening or deformation gradients. A variational model is proposed to describe nonlinear strain hardening, incorporating prior deformation history and using the Mises yield criterion. Finite element analysis is employed to simulate stress and strain distributions in star-shaped tubes with eight beams and deep corrugations, revealing significant variations in yield strength across passes. Stress intensity distributions show how deformation progresses from uniform profiling in early passes to localized stress concentration in later stages. The study also evaluates plasticity reserve usage at critical points, demonstrating that intermediate heat treatments are essential for materials like Grade 1 titanium to prevent failure. Overall, multistage profiling enhances material plasticity and product quality compared to single-pass methods, though detailed computational analysis is necessary to optimize process parameters and tube dimensions effectively.