Abstract
Although the CNC incremental forming process permits thin shell parts of great depth to be formed with multi tool-path schedules, the process causes remarkable thinning to the thin shell parts. In order to suppress the thinning, a new CNC incremental forming process with ORIGAMI method, in which a shell is formed from a flat blank by means of pre-bending (ORIGAMI process) and subsequent incremental stretch-expanding, has been developed. Automotive trunk-lid type panels are formed from aluminum and its alloy blanks by means of the process, and the influence of tool-path schedules, materials properties and forming conditions on the minimum wall-thickness of the panel are examined. It is found that there is a linear relationship between the amount of thinning and the height of stretch-expanding, since the straining in the stretch-expanding process is in plane strain. Experimental results show that the process is suitable for suppression of the thinning.
