Draw Bending Method of Seizure for Pure Titanium Sheet

Abstract

In order to evaluate the seizure of pressing process, we adopted a draw bending method to use pure titanium sheets of 1.0mm in thickness (JIS TP340, ASTM Grade2). The draw bending method was simulated under the conditions of die wall for pressing the glasses frame. The titanium sheet was dragged into the clearance between upper punch and die by the fall motion of the upper punch. The seizure occurred at the shoulder part and side wall part of die. The working conditions changed within the bending radius of die, the lubricating condition and punch speed. The surface roughness of titanium sheets and die surface were measured by the surface measuring instrument using PGI (Phase Grating Interferometry) system (Taylor Hobson Form Talysurf 1200). The surface roughness and the punch load increased intensely within a 10mm of sliding distance under the non-lubricant condition, and increased gradually within a range of 10 to 50mm in every die radius. The load of draw bending process was related to the variation of surface roughness. The seizure of the pressing process, occurring between the surfaces of specimen and die, was estimated by measuring the arithmetic mean roughness.