Convex Laser Forming with High Certainty

Laser forming is a flexible sheet metal forming technique using laser induced thermal distortion to shape sheet metal without hard tooling or external forces. Concave laser forming can be readily achieved, while convex forming could be done under buckling mechanism but whether convex forming is actually obtained heavily depends on the initial strain/stress state of the sheet. A new laser-scanning scheme is postulated to obtain convex forming insensitive to the initial state. The postulate is validated by experimental and numerical results. How the parameters of the scanning scheme affect the certainty of the convex forming, and dependencies of bend angle on Fourier number, laser power, and dimensionless velocity are further investigated experimentally and numerically. The simulation results are in agreement with experimental observations. The numerical simulation model developed is also used to study the transient temperature, stress, and strain state and provide further insight to the process.