Metal flow characteristics of local loading forming process for rib-web component with unequal-thickness billet

Abstract

To explore the metal flow and filling law of large-scale rib-web component local loading forming process is important for fast design of unequal-thickness billet (UTB), parameter optimization and process control of the rib-web component local loading forming process. T-shaped component forming under UTB can reflect the forming characteristics in the large-scale rib-web component forming process. In the forming process by using UTB, the width of local loading changes dynamically, the thickness difference of billet changes notably, and the boundary conditions are very complex. By introducing new assumptions, variables and boundary conditions, a mathematical model for local loading pattern caused by UTB is established by using slab method (SM). Based on the virtualizing experimental data observed by finite element method (FEM), a predicted model for the dynamic width of local loading is established by using polynomial regression and partial least squares (PLS) regression. Comparing with FEM results indicates that the relative differences are less than about 10 % for predicted model of local loading width. Comparing with FEM and physical modeling experimental results indicates that the relative differences are less than about 15 % for SM model. The metal flow, cavity fill, and increased width of local loading under local loading condition are studied by using the mathematical models and numerical simulation, and the results indicate that: the metal flow and deformation pattern under local loading are determined by the thickness of billet and the width of local loading; the increased width of local loading is determined by initial geometric parameters, and the forming parameters such as materials (Ti-6Al-4 V and Ti-6Al-2Zr-1Mo-1 V), loading speed (0.1–1.0 mm/s), temperature (950–970 °C), etc. have little influence on it; the value of xk (position of neutral layer) under local loading pattern caused by geometric parameters of billet is less than that caused by geometric parameters of die at initial forming stage.