Single point incremental forming of a Titanium alloy car body component superimposing a temperature increase

In the present work the possibility of producing a scaled Ti alloy (Ti-6AI-4V) automotive component (car door shell) by Single Point Incremental Forming (SPIF) is investigated. Such a process allows to create a stress and strain distribution in the blank able to postpone the fracture occurrence, thus determining large strain values, normally much higher than limit strains of the material Forming Limit Curve. In addition, the effect of a temperature increase due to both electric heating and tool rotation was used for improving the material formability: in fact, while the experimental equipment allowed to pre-heat the blank, the tool movement allowed to locally increase the temperature. Tests were carried out adopting different levels of the rotation speed, while simultaneously changing the most effective process parameter (pitch) with a fixed tool diameter (16mm). Temperature during the forming process was continuously measured in the central area of the blank using a pyrometer. In addition a Digital Image Correlation system was used for measuring the strain distribution over the incrementally formed blank. In order to investigate the effect of both the tool rotation and the pitch on the SPIF process, the major strain and maximum thinning of the formed blank were analyzed. In addition, the profile of the specimens along a common cutting direction was measured and compared with the desired profile.