An optimized irradiation strategy and layout configuration in laser forming of copper/aluminum bi-metal sheets with a functional thickness

Laser forming process is a type of thermo-mechanical forming process in which a laser beam irradiation on a specific scan path is used to create a bending angle in a sheet. In this work, the forming behavior of copper/aluminum bi-metal sheets with a functional thickness is investigated using the laser forming process. For that, numerical simulations are performed with an implementation of DFLUX subroutine to have more realistic process circumstances. The process parameters were defined as follows: laser beam radius of 2 mm and scan velocity of 1000 mm/min with three different laser power to activate the temperature gradient mechanism. A detailed discussion has been done on an optimized selection of bi-metal sheet layout (i.e. the selection of the material from copper and aluminum as the top layer to increase the formability of the sheet under the same process conditions). Furthermore, the laser forming process of bi-metal sheets with a functional thickness as well as single-layered uniform sheets have been studied and the differences between these two are specified. An irradiation strategy was also presented to eliminate/reduce edge effects on bi-metal sheets. Hence, by adding an auxiliary laser path perpendicular to the main scan path, the uniformity of the final product would be improved. Numerical simulations were fully validated with the corresponding experimental tests. Finally, aluminum was determined as the ideal option to choose as a top layer due to having a higher thermal expansion coefficient and lower thermal conductivity.