Improvement of Forming Accuracy Using Measured Shape of Sheets Formed by Friction Stir Incremental Forming

Abstract

In friction stir incremental forming, formed shape becomes a little smaller than objective one due to springback. To improve forming accuracy, tool path was modified by experimentally obtained calibration equation. A5052 aluminum alloy sheets which size was 150 mm x 150 mm x 0.5 mm were employed for specimen. A hemispherical tool with a diameter of 6 mm was used. The tool was rotated at 10000 rpm and moved at 3000 mm/min and sheets were formed into a frustum of conical shape which height of 20 mm and wall angle of 25 °. Distance from the edge of blank holder to start position of forming was changed and errors of initial diameter of a frustum of cone, forming height and bottom diameter were measured. Errors of wall angle and overall shape were measured due to springback. By modification of tool path, errors of initial diameter, forming height, bottom diameter and wall angle were improved from 7.62 mm to 0.23 mm, 4.76 mm to 0.16 mm, 2.27 mm to 0.27 mm and 1.09 ° to 0.12 °, respectively.