Laser-assisted Gas Incremental Forming of sheet metal

The present study proposes an innovative approach in sheet metal forming, named laser-assisted gas incremental forming, that combines a local laser heating with the action of a pressurized gas to incrementally deform metal blanks. Circular blanks were clamped at their borders using a specifically designed setup and subjected to the action of the pressurized gas on their lower surface, while being locally heated by a laser beam acting on the upper surface. Experiments were conducted with both a stationary and a moving laser spot, varying the laser power, the gas pressure and the laser scanning speed. Temperatures acquired by thermocouples allowed to both define the laser parameters and tune a 2D thermal model used to reproduce and investigate the heating phase of the process. The deformed profile as well as the thickness distribution were measured after the forming process. Metallographic analyses both before and after the forming process were conducted to analyse the microstructural evolution of the alloy during the forming process. Analyses revealed that the final shape of the samples deformed with a stationary spot was symmetric and well-fitted by a Gaussian profile, while when moving the laser spot along a linear track, the final shape and the thickness distribution got asymmetrical, the maximum thinning remained located close to the end of the linear track and, additionally, it decreased as the laser scanning speed increased (due to the shorter interaction time between the material and the laser radiation). Results demonstrate that, thanks to the very local heating, the deformation can be tailored not only spatially but also quantitatively by changing both the laser trajectory and the process parameters.