Optimization of Titanium Grade 2 sheet forming by roller blank holder method

Abstract

Incremental forming is a rapid prototype production method, which can be used in different industrial applications. In this context, it can be used especially in forming of Titanium Grade 2 sheet as depending on the types of manufacture. The main problem of the incremental forming method is that the wall thickness of the piece obtained after the process is not homogeneous. In this study, Titanium Grade 2 sheet was formed 60° axially symmetrical cone geometry using the roller blank holder method (TPIF-RL), which is a new approach. This method provides bigger wall thickness than the conventional incremental forming method considering its results. In this study, it was aimed to investigate the effectiveness of the new roller blank holder method on titanium material. In the experiments, the axisymmetrical piece with a height of 40 mm was formed (the forming angle is 60° with the horizontal). Feedrate, clamping pressure, increment, and forming tool diameter were used as parameters. Forming force, surface roughness, and wall thickness distributions obtained as a result of experimental studies were examined statistically. The interactions of the parameters were evaluated, and optimum levels of forming parameters were determined for the roller blank holder method. In addition, by using gray relational analysis, parameter levels of three dependent variables (forming force, surface roughness, and sheet thickness) were defined to optimize at the same time. As a result, bigger wall thickness was obtained with a low clamping force considering roller blank holder method. It was determined the levels that optimize the three parameters together were 2 bar pressure, 500 mm/min feed rate, 0.25 mm increment, and 5 mm forming tool diameter. Bigger wall thickness was obtained with a low clamping force considering roller blank holder method.