Analysis of forming of tailor welded blanks square box based on strain path

For tailor-welded blanks (TWBs) square box, adopted the self-made hydrostatic press and the square box mould with split binder, the forming strain path, the welded-line movement and the forming limit depth were analyzed by the numerical simulation and the stamping experiment with various technological parameters. The results mainly show that the value and distribution of thick/thin blank holder force have significant influence on the forming strain path in the fracture dangerous position and the formability, and the proper distribution of blank holder force can adjust the fracture site, reduce the welded-line movement and increase the formability; that the larger is the corner radius of die, the higher is the formability of TWBs square box; that the fracture occurs to the round angle of thin material for the lower thickness ratio, the fracture appears in the thin material near the welded seam of the box bottom for the greater movement of welded seam of the higher thickness ratio; that the size and shape of TWBs have significant influence on the fracture site and the formability. To sum up, for tailor-welded blanks (TWBs) square box, the thin material near the welded seam of the box bottom and the round angle the side wall in thin material are considered as the fracture dangerous positions, and the technological parameters are optimized which are the value and distribution of thick/thin blank holder force, the corner radius of die, the thickness ratio, the size and shape of TWBs, so that the formability can be increased by altering the forming strain path, adjusting the fracture site and reducing the welded-line movement.